this science blog

Extremely Young and Incredibly Old

2011-03-10T01:05:00.004+01:00

here's my new story about a newly discovered cluster of galaxies, which is located in the young Universe but it is, surprisingly, already pretty old... enjoy :-)

An old galaxy cluster discovered in the young Universe

Astronomers working with data from several observatories, including ESA's XMM-Newton, have discovered the most distant, mature galaxy cluster yet. The cluster is seen as it was when the Universe was only about a quarter of its current age. In contrast to other structures observed in the young Universe, this object is already in its prime, as is evident from its diffuse X-ray emission and evolved population of galaxies. This shows that fully-grown galaxy clusters were already in place this early in cosmic history. More...

Image Credits: ESA/ESO/Subaru/R.Gobat et al.

Dark stuff that matters

2011-02-16T01:17:00.005+01:00

here's a new story, maybe a teeny bit longer than usual, about the dark 'nests' where the most frenzied galaxies in cosmic history are born...

Herschel quantifies the dark matter threshold for starburst galaxies
How much dark matter is needed to trigger a starburst in the cosmic cribs where galaxies are born? A new study, based on data from ESA's Herschel Space Observatory, has revealed that dark matter halos with a mass larger than 300 billion times the Sun's are particularly efficient at igniting massive starbursts, as they house the most active star-forming galaxies in the Universe. Astronomers have discovered this key threshold by measuring small fluctuations in the Cosmic Infrared Background, the integrated diffuse emission produced by the dust from every galaxy that ever existed. These fluctuations trace the distribution of otherwise mostly unresolved star-forming galaxies and of the dark matter halos that enshroud them. More...

Image credits: The Virgo Consortium/Alexandre Amblard/ESA

When a candle gets 'crabby'

2011-01-19T00:34:00.010+01:00

Here's a new story about what is standard and what isn't — in astronomy. Incidentally, setting and adjusting to new and old standards is a topic which I recently find more and more interesting when applied to a number of other contexts as well...

The Crab Nebula: standard candle no more?

Teaming up with other telescopes monitoring the Crab Nebula, ESA's INTEGRAL observatory has made a significant contribution to demonstrating that this source, previously believed to be a standard candle, might not be so reliable, after all. The small, but measurable dimming of what was until now considered to be one of the brightest and, most importantly, the steadiest source in the high-energy sky calls for a re-examination of how X-ray and gamma-ray observations are calibrated. More...

Image credits: X-ray: NASA/CXC/SAO/F. Seward; Optical: NASA/ESA/ASU/J. Hester & A. Loll; Infrared: NASA/JPL-Caltech/Univ. Minn./R. Gehrz

Lots of cool stuff

2011-01-19T00:13:00.009+01:00

after a long break I'm back with no less than 5 new articles about what can arguably be described as my favourite spacecraft, Planck!! the stories cover a bunch of really cool results that have been achieved from its early data and presented at a conference in Paris last week, spanning a wide range of astronomical objects that will suit everyone's palate — from tiny dust grains in our Galaxy all the way to the huge galaxy clusters and the distribution of galaxies on the largest scales. enjoy :)

Planck's first science results and the release of an extensive compact source catalogue
The Planck Collaboration presents the first science results to emerge from the mission, covering compact and diffuse foreground emission sources, at a conference held from 10 to 14 January 2011 in Paris, France. These results are accompanied by the release of the first Planck product to be publicly distributed: the Early Release Compact Source Catalogue, a highly robust compilation of compact sources detected in each of the telescope's nine channels. Eagerly awaited by the scientific community, the catalogue contents span a wide variety of astronomical sources, and also includes a sample of galaxy clusters detected through the Sunyaev-Zel'dovich effect and a list of cold molecular cloud cores distributed throughout the Milky Way. More...

Planck's successful hunt probes galaxy clusters on very broad mass range
The first all-sky survey of galaxy clusters detected via the Sunyaev-Zel'dovich effect is amongst the highlights presented by the Planck Collaboration at a conference held from 10 to 14 January 2011 in Paris, France. The survey, which has benefited from a fruitful collaboration with ESA's XMM-Newton observatory, probes a wide range of cluster masses and other properties, which is unprecedented for a Sunyaev-Zel'dovich sample. Along with the first results enabled by the survey, the Early Sunyaev-Zel'dovich Cluster sample is being publicly released, providing the community with a robust data set for further studies and follow-up observations of galaxy clusters. More...

Planck traces the coldest objects in the nearby Universe
With its power to detect cosmic material at unprecedentedly low temperatures, Planck has completed the first unbiased, all-sky survey of compact cold and dusty objects in the Milky Way and, at the same time, the first all-sky survey of cool dust in other galaxies. These extensive data sets allow astronomers to shed new light on the earliest phases of star formation. The public release of the Planck Early Cold Core Catalogue will offer the community a large number of new, cold galactic targets to be studied with other telescopes, including ESA's Herschel Space Observatory. More...

Planck sees new, mysterious components in Milky Way and Magellanic Clouds
Thanks to its broad spectral coverage and very high sensitivity, Planck is peering deep into the interstellar medium of the Milky Way and discovering new components and physical mechanisms taking place therein. The results emerging from Planck's first all-sky survey include strong evidence for the presence of extremely rapidly spinning dust grains, an excess emission explained in terms of a previously poorly quantified 'dark gas' and the characterisation of an excess emission arising from the interstellar medium that permeates the Small Magellanic Cloud, a nearby galaxy orbiting our own Milky Way. More...

Planck sees traces of early structure formation in the cosmic infrared background
While targeting the Cosmic Microwave Background, Planck has also captured another important diffuse radiation, the Cosmic Infrared Background, which consists of the light emitted by all galaxies since their formation. This signal, detected by Planck at submillimetre wavelengths, exhibits a high degree of structure and enables astronomers to investigate the still unclear link between star-forming galaxies and the underlying distribution of dark matter, up to the earliest phases of the formation of cosmic structure. More...

Image credits: ESA and the Planck Collaboration

Just like archaeologists

2010-12-03T13:27:00.003+01:00

here's a new article about astronomical measurements of radioactive elements in some stars that remind us of the way archaeologists date their samples. apparently, a highly appreciated comparison!! enjoy :-)

INTEGRAL helps unravel the tumultuous recent history of the solar neighbourhood

Just like archaeologists, who rely on radioactive carbon to date the organic remains from past epochs, astronomers have exploited the radioactive decay of an isotope of aluminium to estimate the age of stars in the nearby Scorpius-Centaurus association, the closest group of young and massive stars to the Sun. The new observations, performed in gamma rays by ESA's INTEGRAL observatory, provide evidence for recent ejections of matter from massive stars that took place only a few million years ago in our cosmic neighbourhood. More...

Image credits: ESA

Hot gas fountains and the galactic spa

2010-11-19T23:12:00.000+01:00

here's a new article that came out today about new data confirming a mechanism where hot gas bursts out of the Milky Way's disc and into the galactic halo, giving rise to so-called galactic fountains:

New evidence for supernova-driven galactic fountains in the Milky Way

Observing the X-ray-bright gas in the halo of the Milky Way, ESA's XMM-Newton has gathered new data which favour a process involving fountains of hot gas in our Galaxy. Such a scenario, with the gas flowing from the galactic disc into the halo where it then condenses into cooler clouds and subsequently falls back to the disc, confirms the importance of supernova explosions in forging the evolution of the interstellar medium and of the entire Galaxy. More...

Image credits: ESA

lenses in the sky – without diamonds

2010-11-04T19:32:00.006+01:00

and finally a new story about cosmology and a good old friend of yours truly, i.e. gravitational lensing... yay!

New method reveals gravitationally lensed galaxies in Herschel-ATLAS first survey

Astronomers using early data from one of the largest projects to be undertaken with the ESA Herschel Space Observatory have demonstrated that virtually all bright sub-millimetre galaxies in the distant Universe are subject to gravitational lensing, which amplifies their flux thus easing their detection and characterisation. Analysis of less than three per cent of the entire Herschel-ATLAS survey, which probes the distant and hidden Universe, yielded a first sample of five lensed galaxies and paves the way for the compilation, in the near future, of a rich catalogue of distant, star-forming and dust-obscured galaxies. More...

Image credits: ESA/NASA/JPL-Caltech/Keck/SMA

hidden magnetism

2010-10-14T22:06:00.006+02:00

lots of new stories these days – yay!
this one's about a really curious object... enjoy :-)

Are most pulsars really magnetars in disguise?

Astronomers using XMM-Newton and other world-class X-ray telescopes have probed a curious source, which emits flares and bursts just like a magnetar but lacks the extremely high external magnetic field typical of these objects. The detection of this source, which could be powered by a strong, internal magnetic field hidden to observations, may mean that many 'ordinary' pulsars are dormant magnetars waiting to erupt. More...

Image credits: ESA

you rock — you rule!

2010-10-13T23:38:00.008+02:00

here's a new story about rocks, I mean, asteroids :-)

Hubble and Rosetta unmask nature of recent asteroid wreck

High-resolution images from the Hubble Space Telescope and a rare view obtained, from a unique perspective, by the Rosetta spacecraft provide a comprehensive picture of P/2010 A2, a puzzling body in the asteroid main belt. Although similar in appearance to a comet, this object and its diffuse trail have been exposed as the remnant of an asteroid crash that happened only one and a half years ago. More...

Image credits: ESA – OSIRIS-Team; MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

Venus' draggin' and twistin' atmosphere

2010-10-07T10:31:00.006+02:00

here's a new story I wrote in the last couple of days for ESA about some cool experiments to study the atmosphere of our sister planet Venus:

Venus Express probes the planet's atmosphere by flying through it

ESA's Venus Express is exploring the density of the Venusian upper atmosphere by measuring how much the planet's atmosphere itself slows down or twists the pointing of the spacecraft. New density measurements, centred on the Northern Pole and obtained during these atmospheric drag experiments, show an unexpected inhomogeneous pattern in the atmosphere of our neighbouring planet. More...

Image credit: ESA

It's always sunny in SOHO

2010-09-22T10:11:00.006+02:00

well, I actually meant to write "on SOHO" as in the Sun-watching telescope I just wrote a new story about for ESA... of course it's always sunny there, being outside of the Earth's atmosphere! but since it's been unusually sunny here in Munich for quite some days, the title seemed more than appropriate :-)

and if you want to find out more about observations of the Sun in the past decade and a half... here are a few fun facts:

A change of pace for EIT, the ground-breaking Sun-watching camera

For almost 15 years, the EIT camera on board SOHO transmitted a picture of the solar corona every 12 minutes, providing ground-breaking observations of the Sun that changed our perception and understanding of our star. After a remarkable career, this instrument has now eased into semi-retirement. Although no longer as active as during its heyday, EIT will still provide snapshots of the Sun - at a more leisurely pace. More...

Image credits: ESA/NASA - SOHO/EIT

Planck & clusters: SO cool

2010-09-15T23:55:00.009+02:00

Here is a new story I just wrote for ESA about my favourite satellite, Planck, and its newest observations of big, huge, beautiful galaxy clusters... enjoy :-)

Planck's first glimpse at galaxy clusters and a new supercluster

Surveying the microwave sky, Planck has obtained its very first images of galaxy clusters, amongst the largest objects in the Universe, by means of the Sunyaev-Zel'dovich effect, a characteristic signature they imprint on the Cosmic Microwave Background. Joining forces in a fruitful collaboration between ESA missions, XMM-Newton followed up Planck's detections and revealed that one of them is a previously unknown supercluster of galaxies. More...

Image Credits: ESA/ LFI & HFI Consortia

Eau de étoile

2010-09-02T10:09:00.007+02:00

here's a new story about water being unexpectedly found in an old star dominated by carbon... and a possible explanation for that:

Herschel detection explains the origin of water in a carbon star

ESA's Herschel Space Observatory has detected water vapour in a location previously thought to be impossible - in the atmosphere of an ageing, red giant carbon star. The rich and detailed data provided by Herschel can be explained within a new framework in which ultraviolet photons play a key role. More...

Image credits: ESA/PACS/SPIRE/MESS Consortia

Hard X-rays, tough stuff

2010-08-11T12:43:00.013+02:00

Here's my latest story, just came out today... the topic's pretty technical but I hope I managed to break it down to the basics. Let's see: essentially, a satellite named INTEGRAL is surveying the sky seeking very high-energy photons (in this case, so-called hard x-rays) coming from a series of objects throughout our own Galaxy and from far away galaxies as well. Now, a new method has been developed to make it work even better.

For those (possibly!!) interested in further details... enjoy :-)

INTEGRAL completes the deepest all-sky survey in hard X-rays

A newly developed image analysis technique has significantly improved the sensitivity limits reached by the IBIS imager on board INTEGRAL, resulting in the deepest survey ever compiled of the entire sky in the energy range between 17 and 60 keV. Pushing the instrument towards its very limits, the novel method discloses a vast number of previously undetected faint sources, galactic and extragalactic alike. More...

Image credit: R. Krivonos et al, 2010

The coolest thing

2010-07-05T19:43:00.001+02:00

over a year ago i was blogging about Planck and how all astrophysicists and cosmologists were overwhelmingly excited about its launch... and now, finally my first news story about this brand-new observatory is online!

there's no science yet - just a pretty picture... super pretty actually! or better, super cool :-)

Planck all-sky image depicts galactic mist over the cosmic background

An all-sky image from Planck's recently completed first survey highlights the two major emission sources in the microwave sky: the cosmic background and the Milky Way. The relic radiation coming from the very early Universe is, to a large extent, masked by intervening astronomical sources, in particular by our own Galaxy's diffuse emission. Thanks to Planck's nine frequency channels, and to sophisticated image analysis techniques, it is possible to separate these two contributions into distinct scientific products that are of immense value for cosmologists and astrophysicists, alike. More...

Image Credit: ESA, HFI and LFI consortia.

Just one step away

2010-07-02T00:39:00.012+02:00

finally, after an incubation of several (!) months, the article I wrote with a colleague during my internship at ESO has been published on Science in School! it's about ALMA, a huge radiotelescope that is currently being built in the desert of northern Chile...

...and it's supposed to be read by young kids in their last years of school, so we tried to make it catchy and pedagogic at the same time — tough task, hope it works :-)

The ALMA Observatory: the sky is only one step away

Imagine hiking in the Atacama region, high in the Andes of northern Chile, one of the driest and remotest spots on Earth. At altitudes of 5000 m and higher, life is not easy here: the atmospheric pressure is much lower than at sea level, and oxygen is scarce.

The landscape, dominated by large volcanoes and other mountain peaks, occasionally decorated by salt flats and picturesque formations of ice and snow, hardly resembles a typical view of our planet. Then, in the midst of this arid and abandoned region, you become aware of a gigantic construction — could those be huge satellite dishes?

[...]

Read the full text on the website of Science in School.

In the image, an ALMA antenna on the Chajnantor plateau, in northern Chile. Image credits: ALMA (ESO/NAOJ/NRAO)

The electromagnetic spectrum - reprise

2010-07-02T00:26:00.015+02:00

I am writing this post following a thread that I started over a year ago about a topic that I am very fond of: the electromagnetic spectrum, which I believe is (unfortunately!) not a widely understood concept. ever since I wrote that post, I wanted to spend a few words and explain what all the fuzz is about - but of course I never had time for that...

then, a few months ago, I had the chance to write a story about ALMA, a world-class radio telescope, and since the story was supposed to be addressed to school kids, I thought - what a cool opportunity to try and explain this topic once and for all... so I convinced the editors of Science in School to have a separate box about it. space on the magazine is always scarce, but I tried to do my best - in less than 200 words!!

Detecting astronomical objects along the electromagnetic spectrum

Visible light is just a small part of the whole spectrum of electromagnetic radiation. The different parts of the spectrum, or spectral bands, are, in order of decreasing wavelength and increasing frequency: radio waves (including microwaves and (sub)millimetre radiation), infrared, visible, ultraviolet, X-rays and gamma rays.

Because different physical processes in the Universe emit light at different wavelengths, each class of objects in the Universe shines most brightly in one or several particular spectral bands. Modern astronomers often try to target many bands, using different telescopes, since each set of observations provides a complementary piece of the puzzle; this approach is called multi-wavelength astronomy.

However, Earth’s atmosphere complicates matters, because it absorbs most of the radiation. Although this protects us, it makes life difficult for astronomers: only a tiny fraction of the electromagnetic spectrum is observable from the ground, and often in these cases, the quality of the observations strongly depends on the geographical site. This is why choosing an excellent site such as Chajnantor for ALMA is so important. In other spectral bands, especially at very short wavelengths, astronomers need telescopes aboard satellites in orbit around our planet, outside the obscuring layer of the atmosphere.

---

The image above displays the atmospheric opacity - the level of the brown curve represents how opaque the atmosphere is at the given wavelength. The major windows are at visible wavelengths (marked by the rainbow) and at radio wavelengths from about 1 mm to 10 m. Observations at wavelengths where the atmosphere is opaque require space telescopes.

Image credits: ESA/Hubble/F.Granato

X-rays, spectra and neutron stars

2010-06-21T14:06:00.007+02:00

or, in other words, here's my new story:

XMM-Newton line detection provides new tool to probe extreme gravity

A long-sought-after emission line of oxygen, carrying the imprint of strong gravitational fields, has been discovered in the XMM-Newton spectrum of an exotic binary system composed of two stellar remnants, a neutron star and a white dwarf. Astronomers can use this line to probe extreme gravity effects in the region close to the surface of a neutron star. More...

Image credits: ESA

More planets in the Universe - yay!

2010-06-17T00:42:00.011+02:00

and here's an all-new story i wrote for ESA a few days ago... dedicated to all the fans of extra-solar planets - and little green men :-)

CoRoT unveils a rich assortment of new exoplanets

By detecting the faint dimming in the light emitted by stars during a transit event, CoRoT has detected six new exoplanets - each with its own peculiar characteristics - and one brown dwarf. One of these exoplanets, designated CoRoT-11b, has twice the mass of Jupiter and orbits a rapidly rotating star; this type of star is an extremely difficult target for exoplanet searches and its detection marks a significant achievement for the CoRoT team. More...

Image credits: CNES

Galaxy Clusters Rock

2010-05-31T14:43:00.010+02:00

here's another news story I wrote that came out today... and again it's about two big, huge, massive galaxy clusters - yay!

Novel observing mode on XMM-Newton opens new perspectives on galaxy clusters

Surveying the sky, XMM-Newton has discovered two massive galaxy clusters, confirming a previous detection obtained through observations of the Sunyaev-Zel'dovich effect, the 'shadow' they cast on the Cosmic Microwave Background. The discovery, made possible thanks to a novel mosaic observing mode recently introduced on ESA's X-ray observatory, opens a new window to study the Universe's largest bound structures in a multi-wavelength approach. More...

enjoy :-)

Image credits: ESA/XMM-Newton; Background image: Blanco Cosmology Survey/NOAO/AURA/NSF; SZE contours: South Pole Telescope/NSF

A wealth of infrared stories

2010-05-06T15:38:00.020+02:00

this week i'm reporting from the Herschel First Results Symposium, ESLAB 2010, held at the European Space Research and Technology Centre, Noordwijk, The Netherlands. stated this way it does sound cool!

and finally my first 3 stories for ESA's Science & Technology website are online... they're intended to some sort of "interested" readership, but I guess it'll do no harm posting them here as well... :-)

they're about ESA's brand new space observatory, Herschel, which was launched almost a year ago and is now peering at the skies in the far-infrared domain of the electromagnetic spectrum.

the stories tell about some of the first results about 3 different types of objects on 3 very different cosmic scales: far, far away galaxies, massive stars forming in our own Galaxy and tiny water molecules in the regions where stars are formed. quite a spread of topics: take your pick!

Herschel reveals galaxies in the GOODS fields in a brand new light
The discovery of a previously unresolved population of galaxies in the GOODS fields and the first measurements of properties of galaxies in the almost unexplored far-infrared domain are among the first exciting scientific results achieved by Herschel's PACS and SPIRE instruments. These findings confirm the extraordinary capabilities of ESA's new infrared space observatory to investigate the formation and evolution of galaxies. More...

Herschel unveils rare massive stars in the act of forming
New images from ESA's Herschel space observatory reveal high-mass protostars around two ionised regions in our Galaxy. The detection of these rare stars in an early phase of evolution is key to understanding the mysterious formation of massive stars. More...

Herschel's HIFI follows the trail of cosmic water
Herschel's HIFI instrument was especially designed to follow the water trail in the Universe over a wide range of scales, from the Solar System out to extragalactic sources. Early results, presented this week at the Herschel First Results Symposium, demonstrate how HIFI uses water to probe the physical and chemical conditions in different regions of the cosmos. More...

Image credits: ESA/PACS Consortium/PEP Key Programme Consortium; ESA, PACS & SPIRE Consortia, A. Zavagno (Laboratoire d'Astrophysique de Marseille) for the Herschel HOBYS and Evolution of Interstellar Dust Key Programmes; ESA and the HIFI consortium; D. Johnstone for the WISH Key Programme (Background image: NASA/JPL-Caltech/S.T. Megeath, Harvard-Smithsonian CfA).

A "massive" press release

2010-05-05T14:34:00.010+02:00

this is a photo release I wrote a couple of months ago while I was still an intern @ESO, but it just got published today... well, I wrote many more while I was there, but they were mostly about (arguably!) boring clouds of dust and gas where stars are born... this time instead I managed to write about real stuff for a change! finally something MASSIVE i.e. a galaxy cluster and weak lensing! and since the image was not that new, I made it pretty pedagogical, so here it is... enjoy :-)

A Cluster and a Sea of Galaxies

A new wide-field image released today by ESO displays many thousands of distant galaxies, and more particularly a large group belonging to the massive galaxy cluster known as Abell 315. As crowded as it may appear, this assembly of galaxies is only the proverbial “tip of the iceberg”, as Abell 315 — like most galaxy clusters — is dominated by dark matter. The huge mass of this cluster deflects light from background galaxies, distorting their observed shapes slightly.

When looking at the sky with the unaided eye, we mostly only see stars within our Milky Way galaxy and some of its closest neighbours. More distant galaxies are just too faint to be perceived by the human eye, but if we could see them, they would literally cover the sky. This new image released by ESO is both a wide-field and long-exposure one, and reveals thousands of galaxies crowding an area on the sky roughly as large as the full Moon.

These galaxies span a vast range of distances from us. Some are relatively close, as it is possible to distinguish their spiral arms or elliptical halos, especially in the upper part of the image. The more distant appear just like the faintest of blobs — their light has travelled through the Universe for eight billion years or more before reaching Earth.

Beginning in the centre of the image and extending below and to the left, a concentration of about a hundred yellowish galaxies identifies a massive galaxy cluster, designated with the number 315 in the catalogue compiled by the American astronomer George Abell in 1958 [1]. The cluster is located between the faint, red and blue galaxies and the Earth, about two billion light-years away from us. It lies in the constellation of Cetus (the Whale).

Galaxy clusters are some of the largest structures in the Universe held together by gravity. But there is more in these structures than the many galaxies we can see. Galaxies in these giants contribute to only ten percent of the mass, with hot gas in between galaxies accounting for another ten percent [2]. The remaining 80 percent is made of an invisible and unknown ingredient called dark matter that lies in between the galaxies.

The presence of dark matter is revealed through its gravitational effect: the enormous mass of a galaxy cluster acts on the light from galaxies behind the cluster like a cosmic magnifying glass, bending the trajectory of the light and thus making the galaxies appear slightly distorted [3]. By observing and analysing the twisted shapes of these background galaxies, astronomers can infer the total mass of the cluster responsible for the distortion, even when this mass is mostly invisible. However, this effect is usually tiny, and it is necessary to measure it over a huge number of galaxies to obtain significant results: in the case of Abell 315, the shapes of almost 10 000 faint galaxies in this image were studied in order to estimate the total mass of the cluster, which amounts to over a hundred thousand billion times the mass of our Sun [4].

To complement the enormous range of cosmic distances and sizes surveyed by this image, a handful of objects much smaller than galaxies and galaxy clusters and much closer to Earth are scattered throughout the field: besides several stars belonging to our galaxy, many asteroids are also visible as blue, green or red trails [5]. These objects belong to the main asteroid belt, located between the orbits of Mars and Jupiter, and their dimensions vary from some tens of kilometres, for the brightest ones, to just a few kilometres in the case of the faintest ones.

This image has been taken with the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile. It is a composite of several exposures acquired using three different broadband filters, for a total of almost one hour in the B filter and about one and a half hours in the V and R filters. The field of view is 34 x 33 arcminutes.

Notes:

[1] The Abell catalogue from 1958 comprised 2712 clusters of galaxies, and was integrated with an additional 1361 clusters in 1989. Abell put together this impressive collection by visual inspection of photographic plates of the sky, seeking those areas where more galaxies than average were found at approximately the same distance from us.

[2] Ten percent of a galaxy cluster’s mass consists of a very hot mixture of protons and electrons (a plasma), with temperatures as high as ten million degrees or more, which makes it visible to X-ray telescopes.

[3] Astronomers refer to these slight distortions as weak gravitational lensing, as opposed to strong gravitational lensing, characterised by more spectacular phenomena such as giant arcs, rings and multiple images.

[4] A weak lensing study of the galaxy cluster Abell 315 has been published in a paper that appeared in Astronomy & Astrophysics in 2009 (“Weak lensing observations of potentially X-ray underluminous galaxy clusters”, by J. Dietrich et al.).

[5] The blue, green or red tracks indicate that each asteroid has been detected through one of the three filters, respectively. Each track is composed of several, smaller sub-tracks, reflecting the sequence of several exposures performed in each of the filters; from the length of these sub-tracks, the distance to the asteroid can be calculated.

Image credit: ESO/J. Dietrich

Hubble's birthday and a contest

2010-04-24T15:18:00.015+02:00

Hubble (the Space Telescope!) celebrates 20 years in orbit today... yep, it was 1990 when they kicked this bus-sized observatory out in space, although it was not until late 1993 that it started delivering "pretty pictures", due to a sperical aberration in the mirror which had to be fixed via a manned servicing mission.

But then, it was like a bullet set free: the nineties of last century were literally flooded with Hubble images, which went all the way from science magazines to all sort of products, ranging from desktop screensavers to super-cool animations in sci-fi movies, and so on... I was a teenager in those years (and kind of a "star-struck" one must I add) so I remember that pretty well, and I have no hesitation (although I did not study art nor communication) to state that Hubble images have largely affected the field of graphic design and, at the same time, the very perception of the Universe to the general public's eye.

That's why I'm promoting this contest, launched in honour of Hubble's 20th: search for Hubble images in popular culture and how they contributed shaping it. I find it pretty cool. Well, I must add I had quite a say in the whole thing... ;-) but I really think it will be nice, in the end, to look at all the funny pics collected by people all around the world.

If you're interested in the inter-connection between astronomy, science and popular culture, have a look at these two articles on related issues from The Guardian:
Art: the final frontier - 1st February, 2010
How science became cool - 13th April, 2010

In the image, likely Hubble's most iconic shot, are the so-called "pillars of creation", huge structures of gas and dust, in the Eagle Nebula, where newborn stars come to life. I must shyly admit this was my first desktop background in the late 1990s...
Credits: Jeff Hester and Paul Scowen (Arizona State University), and NASA/ESA.

Venus Express Celebrates Four Years of Orbit and Discoveries

2010-04-11T10:43:00.012+02:00

ESA’s Venus Express spacecraft celebrates today its fourth anniversary orbiting our planetary neighbour. During these four years of operations, the mission has thoroughly surveyed the atmosphere of Venus, unveiling several mysteries about the climate on this planet and highlighting some similarities with the one on Earth.

Launched on November 9, 2005 from the Baykonur cosmodrome in Kazakhstan, Venus Express was successfully inserted in orbit around the planet on April 11, 2006. Its elliptical orbit is highly eccentric, with a pericentre height of only 250 km and an apocentre distance of about 66,000 km. The choice of such an orbit makes both observations from a global point of view and zooming on certain regions possible. The so-called nominal mission took place between June 2006 and October 2007, a total of about 500 Earth days, which correspond to only two days on Venus, due to this planet’s extremely slow rotation; the mission kept collecting data in the following years as well, and most likely will continue until 2013.

Venus Express has enormously increased our knowledge about this planet. Thanks to these extraordinary data, it is now possible to characterise the distribution and composition of clouds on Venus in unprecedented detail.

Amongst the seven instruments on board Venus Express, the Venus Monitoring Camera (VMC) and the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) have investigated the thick layer of clouds covering Venus between 50 and 70 km above surface. The stunning images delivered by the two instruments, thanks to their exceptional spatial resolution ranging between 50 km to a few hundred metres, highlighted different patterns in the structure of the clouds. Patchy and fragmented clouds at low latitudes show the importance of tumultuous convective phenomena in the equatorial region, where the solar heating is more intense; this mottled scenario smoothly changes into a more streaky structure at mid latitudes, and into circular and spiral features in the polar regions.

The global vortex-like structure of Venus clouds is confirmed by a particularly striking feature, revealed in the infrared wavelengths by VIRTIS: a huge eddy rotating around the southern pole, its appearance varying from oval to S-shaped. Although the eye of this hurricane, about 1500 km across, is much larger than the typical size of hurricanes on Earth, this structure highlights a morphological similarity with the distribution of clouds on our own planet.

Another instrument aboard Venus Express, the Ultraviolet and Infrared Atmospheric Spectrometer (SPICAV/SOIR), studied the planet’s atmosphere indirectly, through a method called stellar occultation. As the spacecraft moves around Venus, its line of sight to a given star moves through the atmospheric layers, and the absorption of such light due to material in the atmosphere changes accordingly. By monitoring these variations over a sample of 30 stars, it was possible to probe the vertical structure of the atmosphere of Venus, revealing an upper haze that surprisingly extends up to an altitude of 90 km.

Besides these exciting discoveries regarding the morphology of the planet’s clouds, during the past four years Venus Express also conducted extensive studies of the atmospheric composition and even peered through it, exploring the surface of the Earth’s sister planet.

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This story was also an exercise (and a pretty successful one I must say!) and is based on "Venus express: Highlights of the nominal mission" by D.V. Titov et al, published in 2009 on Solar System Research, Volume 43, Issue 3, pp.185-209.

In the images:
* An artist's impression of Venus Express
(Credits: ESA; Image by AOES Medialab)
* A map of the venusian clouds, with infrared (lower left) data derived from the Visible and Infrared Thermal Imaging Spectrometer, VIRTIS, on the planet’s night-side and ultraviolet (upper right) data captured by the Venus Monitoring Camera, VMC, of the day side
(Credits: ESA/MPS/DLR/IDA and ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA)
* The ‘eye of the hurricane’ close to Venus's south pole (indicated by a yellow dot) as imaged by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on board Venus Express
(Credits: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA/Univ. of Oxford)

Job Hunting in the Galaxy Zoo

2010-04-01T13:56:00.020+02:00

Massive help from citizen scientists opens new paths for full time astronomers

We are all under the same sky. Sooner or later, we all raise our eyes to gaze at the stars in the celestial vault and wonder about the mysteries of the Universe. As humankind is tied to the skies, it is natural to expect a large participation in citizen science projects inspired by astronomy. However, the massive success of “Galaxy Zoo” exceeded expectations and lead the venture to the next phase, even opening up brand-new academic positions.

Citizen scientists are members of the public that contribute to genuine scientific research. They might count birds, fish or stars, play with proteins on their computers or look for oddities in images of the cosmos, and then send their results back to professional scientists. A long-established tradition for researchers, resorting to the so-called power of the crowds yields myriad benefits to both groups.

The “Galaxy Zoo” project has been running for almost three years. The organisers, a group of astronomers based in the UK and US, had the ambitious goal of asking the public to classify the shapes of a million galaxies. The zoo analogy is striking, as galaxies in the Universe have a plethora of different morphological features; when it comes to their overall shape, however, astronomers have basically two choices: spiral or elliptical.

Understanding the shape of a galaxy goes well beyond a simple catalogue compilation, as it identifies its formation and dynamical history: stars in a spiral galaxy rotate around the centre in an ordered fashion, whereas in an elliptical galaxy they move in a much more chaotic way. Beautiful images of nearby galaxies are usually straightforward to interpret, their stunning spiral arms or roundish appearance leaving astronomers with little doubt. Far away galaxies, instead, look more like small, undefined blobs and sorting them into these two classes is an extremely delicate task.

In the past decades, countless graduate students have devoted years to the classification of galaxy shapes, which is mostly performed via visual inspection. Even though modern astronomy is a highly computer-dominated discipline, it is not trivial to teach a machine how to recognise shapes, and the human brain is still the most powerful tool in this context. Given these premises, the potential of a scheme to involve citizen scientists in galaxy classification was huge, and the “Galaxy Zoo” team has fully exploited it.

Only a few days after the launch of the project’s website, 35 000 enthusiasts had completed the same amount of work that a graduate student could have performed devoting months to this sole task. Employing the public in these operations does not demote professional astronomers; instead, it enables them to perform research with plenty of new, fresh data, without having to perform the “dirty” job themselves. Using the “Galaxy Zoo” samples, astronomers have learned new, exciting details regarding the evolution and the distribution of different galaxies, and even discovered some unexpected and never-before-seen features. More than a dozen papers have already been published in international journals, and many others are in progress, thanks to the devotion of this immense community that self-styled themselves as “Zooites”.

After the first successful results, the project has already moved to the next level: a new online sample of galaxies is ready to be characterised in much greater detail than the previous one; members of the public can also look for additional features, such as mergers between neighbouring galaxies. And there’s more, as the project’s next step involves citizen and professional scientists alike.

In order to turn the massive amount of data analysed by the community into proper results, one or more astronomers have to devote their entire energies to the “Galaxy Zoo” cause. On March 1st, a postdoctoral researcher will start working full time on this project at the University of Oxford, where it all began; soon another post-doc position will be filled at the University of Nottingham, and the Adler Planetarium, an astronomy museum with an active research group in Chicago, is recruiting scientists and software developers to join the “Galaxy Zoo” team.

This and other projects have provided innumerable members of the public with a chance to share the excitement of scientific discovery and to get a glimpse of how research works. In turn, the citizen scientists have contributed, over the years, to close the circle, dutifully delivering data and occasionally leading to scientific breakthroughs. Now, with citizen scientists literally employing professional astronomers, new research perspectives open: the circle has evolved into a spiral.

----------

This story is also an exercise i wrote just over a month ago...
For more info about the project: www.galaxyzoo.org

Image credits: Galaxy Zoo and the Sloan Digital Sky Survey

On exercises and fires

2010-04-01T13:32:00.012+02:00

this is an exercise i wrote a couple of months ago... it's not about astronomy or physics, for a change. this time it's about earth system science, and i didn't really know much about it before reading the paper. but still, it's an example of how i write, and pretty interesting too. so, here it is:

Not All Fires Warm the World

Planting trees over vast areas of the planet may help to slow climate change, but what if then forest fires heat the world again? Now researchers say there is no need to worry, as northern forest fires may actually contribute to cooling the climate, at least on decade-long time scales.

Speculations about the role of boreal forests, the mainly evergreen woods found at high northern latitudes, in mitigating the effects of man-made global warming have raised the question of forest fires and their possible intensification due to climate changes. Previous studies focussed mostly on the conspicuous quantities of carbon dioxide and other greenhouse gases emitted during fires, highlighting a possible degeneration into a self-feeding loop. However, there is more than greenhouse gases involved in the complex interactions of forest fires with their landscape and the atmosphere.

A new study led by Earth system scientist James Randerson of the University of California, Irvine, sheds new light on the subject through an in-depth analysis of the 1999 Donnelly Flats fire, which destroyed about 7600 hectares of black spruce in interior Alaska.

Besides monitoring greenhouse gases and aerosol emissions, the team investigated the different amount of sunlight reflected by forests and burned landscapes — the so-called albedo. The bare terrain left behind by a fire reflects much more light than the dark forest’s canopy, especially when snow is lying on the ground. A higher reflecting power results in cooling and, when summed together with all other contributions, it alleviates the warming effect caused by other agents. And there is more: over the 80 years following the fire event, it even reverts the score.

Soot produced in the fire and deposited on surrounding snow and sea ice is also a player in the ‘albedo game’, this time reducing the reflecting power of otherwise almost white surfaces. Its contribution increases warming, but becomes negligible after the first year. The loss of canopy, instead, is a long-term phenomenon, as vegetation needs several decades to recover to pre-fire conditions.

Randerson and his team observed the burn perimeter over five years, and complemented these measurements with satellite data surveying the light-reflecting properties of various areas in interior Alaska where fires occurred at several different epochs in the past century.

This extensive study of the overall impact of boreal forest fires on the temperature of both northern regions and the whole planet bears the reassuring finding that fires do not contribute to the Earth’s warming if we consider long enough time scales. It will be interesting to compare these results with studies of Siberian larch forests, and, even further, to apply a similar approach to temperate and tropical ecosystems.

-----------

This story is based on "The Impact of Boreal Forest Fire on Climate Warming", by J.T. Randerson et al., published on Science on 17 November 2006 (Vol. 314. no. 5802, pp. 1130 - 1132).

The photo of the Donnelly Flats Fire, near Delta Junction, Alaska (June 13-20th 1999) is courtesy of Tom Lucas, Delta News Web.

my first proper freelance story!

2010-03-30T14:09:00.012+02:00

last week i managed to write a freelance story for Science NOW, the online news portal of the Science magazine! you can find it here, but i thought i'd share it on my science writing blog :-)

Using Dark Matter to Sense Dark Energy

It's a weird, weird, weird universe we live in. Cosmologists and astronomers know that only 5% of it consists of ordinary matter of the sort found in stars and planets. Another 23% consists of mysterious dark matter that (so far) manifests itself only through its gravity. And a whopping 72% of the universe consists of bizarre, space-stretching dark energy which is speeding up the expansion of the universe. Scientists don't know exactly what dark matter and dark energy are. But now they've pulled off a bit of black magic and used the subtle effects of one to study the other.

Dark matter gives structure to the cosmos. Space is filled with a vast "cosmic web" of strands and clumps of dark matter, which have grown from microscopic variations in the original, nearly smooth distribution of dark matter after the big bang. Through their gravity, the clumps draw in ordinary matter, so the galaxies form and reside within these clumps. Responding to their own gravity, the clumps and strands also grow denser and more compact. At the same time, dark energy stretches the very fabric of space. So if scientists can study the evolution of the cosmic web, they ought to be able to see the effects of dark energy setting in and slightly slowing the growth and coalescence of the clumps.

And that's what astrophysicist Tim Schrabback of the Leiden Observatory in the Netherlands, and colleagues have done. Their study uses data from the Cosmic Evolution Survey, or COSMOS, the largest galaxy survey ever conducted with NASA's orbiting Hubble Space Telescope. Thanks to an improved algorithm to analyze the images, Schrabback's team could study in great detail the shapes of over 446,000 galaxies in a 1.64 square degree patch of sky. During its journey to Earth, the light from these faint galaxies must pass through the lumps and filaments of dark matter in the cosmic web. The gravity exerted by the clumps bends the paths of light rays and distorts the images of the galaxies, so rather than appearing as randomly oriented ellipses on the sky, neighboring galaxies align a bit like fish in a school. The distortions are tiny, but starting in 2000, astronomers managed to detect the effect, which is known as cosmological weak lensing, in surveys of thousands of galaxies. In recent years, they've even begun to trace, at least crudely, the three-dimensional structure of the cosmic web.

Now, Shrabback and colleagues have gone a key step further and have actually detected the effects of dark energy on the evolution of the cosmic web. This was possible thanks to additional ground-based data which allowed them to estimate distances to almost half of the observed galaxies. Together with the shape measurements, the distances helped the researchers produce a 3D "picture" of the distribution of the dark matter in the cosmic web. This tomographic approach is the cosmic analogous of the "reconstruction of the skeleton from a CT scan," adds team member F. William High from Harvard University.

This 3D view on the "cosmic web" shows how many clumps are to be found at different distances from us, and how massive they are. Comparing the results obtained on the different distance slices, the team recorded a slowing of the growth of cosmic structures, a sign that the dark energy is driving the universe to expand faster and faster. The excellent agreement between these and many other measurements indicates that "cosmologists seem to be on the right track on their quest to understand the properties and evolution of the Universe," notes Schrabback.

"This important result shows the power of weak lensing studies from space to track down dark energy," says Yun Wang, a cosmologist at the University of Oklahoma, Norman. She also points out that, in order to fully exploit this method and attempt to understand what dark energy actually is, "a much wider survey is necessary," such as those planned for the future space-telescope missions such as the United States proposed Joint Dark Energy Mission and Europe's proposed Euclid satellite. "This study demonstrates that the method can work, and anticipates the success of these future experiments," she says.

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This story is based on "Evidence for the accelerated expansion of the Universe from weak lensing tomography with COSMOS" by Schrabback et al. to appear soon in the journal Astronomy & Astrophysics.

The image shows the reconstruction of the total (mostly dark) matter distribution in the COSMOS field, where the colour coding indicates the distance of the foreground mass concentrations as gathered from the weak lensing effect. Structures shown in white, cyan, and green are typically closer to us than those indicated in orange and red. Credits: NASA, ESA, P. Simon (University of Bonn) and T. Schrabback (Leiden Observatory)

Exoplanet live show - next week

2010-02-04T22:53:00.006+01:00

On Saturday, February 13, 2009 the exoplanet XO-3b will transit its parent star. Although the phenomenon itself is not spectacular, as this planet orbits its star in less than four days, it will be accompanied by an extraordinary event on Earth: for the first time ever, a professional telescope will observe the transit and the light curve will be webcast live.

The project is called "Worlds of the Sky", quoting the title of a famous book by Camille Flammarion, and is organised by the Brera and Palermo Observatories of the Italian National Institute of Astrophysics, in cooperation with several associations of amateur astronomers.

The unprecedented event will be broadcast live on the website www.crabnebula.it on February 13, from 7 p.m. on. The webcast will allow users around the world to watch the evolution of the light curve of the star XO-3 as the planet passes in front of it, monitored by the 1.34-metre Ruths Telescope of the Brera Observatory in Merate, Italy. The real-time data will be accompanied by comments of astronomers in English, Italian and Chinese.

The organisers intend to involve as many enthusiasts, students and teachers as possible in this novel outreach project, and wish that amateurs around the globe will monitor the event with their own instrumentation, joining efforts in this planetary "guided" observation of an otherworldly event.

The transit of an exoplanet is one of the main techniques used by astronomers to detect planets orbiting stars other than our Sun, monitoring the variations of a star's brightness. The planet "featured" in this event, XO-3b, was discovered in 2007. It is an extremely massive one, about 13 times as massive as Jupiter, and orbits very closely the star XO-3, also known as GSC 03727-01064, in the constellation Camelopardis. The transit will last about 170 minutes.

A promotional trailer of the event, in English, Italian and Chinese, can be found on YouTube.

Image: the Ruths Telescope of the Brera Observatory in Merate.

Five New Worlds in the Universe

2010-01-08T00:34:00.009+01:00

The first planets discovered by NASA’s satellite Kepler

The Kepler satellite, launched by NASA in March 2009, has started bearing its first fruits. The principal investigators of the space mission searching for planets outside our Solar System announced the first discoveries last Monday, at the annual meeting of the American Astronomical Society, taking place these days in Washington DC, USA.

Five new planets, orbiting stars at distances of more than 100 light-years from our Sun, have been detected during Kepler’s first months of observations. They now join the count of extra-solar planets discovered so far, amounting to over 400. Thanks to advances, obtained only in the past 15 years, astronomers can better understand how planets and planetary systems like our own form around other stars.

The new worlds discovered by Kepler are very different from our planet, being much larger and much hotter than the Earth. Four of them are even larger than Jupiter, the biggest planet in the Sun’s court; only one of them is slightly smaller, with a size similar to that of Neptune, another giant in the Solar System.

Due to their high temperatures of more than 1200 degrees Celsius, it is almost impossible to suppose that these planets host any form of “earth-like” life. However, the goal of the Kepler mission is ambitious: in the upcoming three years of observations it will be very likely that astronomers will detect planets similar to our own, somewhere in our galaxy.

The fact that the first planets to be discovered are giant ones is a sort of “drawback” of the method employed in the search. Kepler makes use of the so-called transit technique: when a planet orbiting a star intervenes between it and us, the star becomes clearly dimmer, as its light is obscured by the planet. Through monitoring hundreds of thousands stars over long time scales, astronomers study how their luminosity varies and can thus reveal the presence of one, or more, planets around them.

The bigger the planet, the more pronounced is its obscuring effect upon the star hence the easier it is to discover. But size isn’t everything, as also the distance from the parent star plays an important role. All five of these worlds lie very close to their sun, and only take a few days to complete an orbit around it. In comparison, the Earth takes a year and Mercury, the closest planet to our Sun, takes about three months to complete a so-called revolution.

The vicinity of these planets to their parent star is indeed another factor in their discoverability: as they orbit so fast around it, they obscure the star very often, thus making it more likely for astronomers to notice over human time scales. A planet that takes months or years to orbit its star is more elusive, although not absolutely impossible to detect.

“It's only a matter of time before more Kepler observations lead to smaller planets with longer-period orbits, coming closer and closer to the discovery of the first Earth analog,” said Jon Morse, director of the Astrophysics Division at NASA Headquarters in Washington.

The discovery of planets located at “reasonable” distances from the star they orbit is a crucial step towards the quest for other worlds that could theoretically host life forms. The so-called “habitable zone” defines the range of distances around a given star where the temperature is such to guarantee liquid water on a planet’s surface. In the case of our Sun, this distance corresponds roughly to Earth’s orbit — closer or farther away, the development of human life “as we know it” couldn’t have been possible.

None of the over 400 planets discovered so far lies in its parent star’s “habitable zone”. However, astronomers believe in Kepler’s capabilities and hope that it will be able to detect some in the upcoming years. Furthermore, the question about the existence of life elsewhere in the universe is not restricted to living forms similar to those inhabiting our own planet. “In other regions of this Universe, everything I can’t even imagine exists,” Bluvertigo (*) sang over ten years ago. Let us be surprised by the unimaginable.

(*) Bluvertigo are an Italian rock band formed in the mid-nineties and still active. The quote refers to the popular song “Altre forme di vita” (translated, “Other forms of life”) from 1997.

The image on top shows Kepler, launched on March 6th, 2009 from Cape Canaveral, Florida, USA. The image below is an artistic representation of one of the newly discovered worlds. Credits: NASA/Kim Shiflett and NASA/JPL-Caltech/T. Pyle (SSC), respectively.

Translated from Il Denaro, 07.01.10

Incidentally...

2009-12-11T01:15:00.005+01:00

... since I've just mentioned Science in School, I guess there is no harm in a little publicity to this magazine I've been collaborating with for almost three years now - mostly translating into Italian, and finally with my first writing effort. ever. (despite the delay...)

It's a great tool for secondary school science teachers and students, with feature articles about the latest discoveries in every scientific field, bios and profiles of scientists and teachers, ideas for didactic activities, and much more...

If you subscribe on their website, you can receive a printed copy of the magazine in English for free. Otherwise, many translations in several European (and non) languages are available online, courtesy of many volunteers and enthusiasts - just like me!

Interview on Science in School

2009-12-11T01:04:00.008+01:00

Finally, after a gestation longer than a year, my interview to Alessandro has finally been published on Science in School!
Here is an excerpt from it:

A star-struck teacher in Italy

Research offers exciting and challenging job opportunities, but sometimes the price to pay in terms of personal sacrifice is very high. CM interviews a young astronomer who found satisfaction in the classroom – teaching mathematics.

Astronomy has always been Alessandro Berton’s greatest passion: after his undergraduate studies at the University of Padua, Italy, he moved to the Max Planck Institute for Astronomy in Heidelberg, Germany, for his PhD. His research focused on the development of new, cutting-edge techniques to detect extrasolar planets. The quest for planets outside our solar system has been one of the most fascinating topics in astronomy for the past 15 years, and Alessandro was thrilled to be a part of it. Yet something was missing.

“During those years, I always felt the lack of social, human interaction – a lack that is typical of many research environments,” he explains. “I longed for a job where I could spend more time with other people than in front of my computer screen.” Hence, a few months after receiving his PhD, Alessandro enrolled in the Italian high-school teacher-training program, and at the same time he began to teach mathematics to his very first students.

[...]

Read the full text on the website of Science in School.

I'm finally on my way to becoming a science & society opinion writer... or, well, whatever. yay!

Physics: the Nobel seizes the light

2009-10-09T00:55:00.002+02:00

The prize goes to Willard Boyle and George Smith, fathers of digital photography

On Tuesday, October 6th, the Nobel Prize in Physics 2009 has been awarded to Willard S. Boyle and George E. Smith, the fathers of digital photography. In 1969, the two scientists from Bell Laboratories, in New Jersey, USA, invented a device able to capture light without using photographic film — the so-called CCD (Charge-Coupled Device).

The technology behind the CCD exploits the photoelectric effect, through which light is transformed into an electric signal. The explanation of the photoelectric effect won Albert Einstein the Nobel Prize in 1921. Boyle and Smith faced the challenge of converting this effect into a practical application, and designed a sensor able to catch light at several different points (called pixels) and to transform it, over an extremely short time lapse, into electric signals to then be transported and reproduced on a monitor or stored in a file.

The CCD has revolutionised photography and our approach to it for ever, as it is the very heart of tens of millions digital cameras produced in the world, including those integrated into many mobile phones and other gadgets. However, digital photography meant an even more remarkable revolution for science, and for astronomy in particular, a field which literally lives off the images of the sky.

All current professional telescopes are in fact equipped with digital sensors, vastly more sensitive than the old photographic plates astronomers made use of until only a few decades ago. Furthermore, CCDs can be used again many times and their output signal, being already in digital form, is ready to be stored and analysed by computers. In fact, without this new technology, it wouldn’t have been possible even to conceive the massive catalogues containing detailed information about hundred of millions of far-away galaxies, which allowed astronomers to understand the properties of the Universe better and better.

Boyle and Smith shared the most prestigious of all scientific awards with physicist Charles K. Kao, for his work concerning the transmission of light signals through optical fibres. Optical fibres, just like the CCD, also contributed to the digital revolution, making the sharing of data and information possible over increasingly short time intervals. Without them, the internet as we know it could not exist.

It is interesting to note how, during the International Year of Astronomy 2009, the Nobel Prize in Physics has been awarded to three scientist whose research focussed on light and has contributed to the production of vital tools for astronomers, professionals and amateurs alike.

Image credit: NASA

Translated from Il Denaro, 08.10.2009

Dr.Rer.Nat.

2009-05-20T20:47:00.001+02:00

Planck and the Cosmic Microwave Background

2009-05-15T01:53:00.012+02:00

The European Planck surveyor satellite will map the entire sky at microwave wavelengths - why is this important? Scientist will be able to scrutinize models which explain the formation of galaxies by measuring fluctuations in the distribution of dark matter, only a mere 300 000 years after the big bang. These fluctuations manifest themselves as small variations of the mean sky temperature of 3 degrees Kelvin and have been generated when the first atoms were formed in cosmic history. From these seed fluctuations larger and larger objects were assembled by gravity which finally resulted in the formation of galaxies and clusters of galaxies. Important cosmological parameters are the amplitude of these seed fluctuations and the mean density of matter, which Planck will be able to measure.

A large part of the scientific programme is devoted to so-called secondary anisotropies: these are fluctuations of the sky temperature which are generated by the interaction of photons of the microwave background with the large-scale distribution of galaxies. There are basically two categories of interactions: gravitational lensing, which can be used for precision measurements of cosmological parameters, and Compton-interactions with electrons of the hot gas inside clusters of galaxies - a potential new powerful way of detecting clusters of galaxies.

Planck's advantage over previous experiments is its high sensitivity and angular resolution: it can measure fluctuations of a few microKelvin, and its angular resolution is better than a tenth of a degree. The survey will be carried out from the Lagrange-point L2, at roughly 1.5 million kilometers from Earth - 5 times the mean Earth-Moon distance. The science team of Planck comprises about 500 scientists who are anxious to see the satellite launched on 14 May 2009, after 15 years of preparation.

Bjoern Malte Schaefer
Appeared in the Italian translation on Il Denaro, 14.05.2009

Image: map of the microwave sky as observed by NASA's satellite WMAP, launched in 2001. Different colours represent the tiny fluctuations in temperature: the difference between red and blue spots is only 0.0002 degrees. Planck's maps will be even more precise than that. Credits: NASA/WMAP team.

A high for geeks

2009-05-15T00:27:00.009+02:00

Ok, these days all the astronomers and astrophysicists I know - and, with me being a geek, this is a substantial fraction of the people I know and hang out with - have been overly excited with the launch of Planck and Herschel, the two satellites I mentioned in the previous post.

Will they launch them?
When?
Why is the launch being constantly delayed later and later?
Will they be launched eventually?
Today?
Tomorrow?
In two weeks?

Please, shoot the freaking rocket!
And indeed, they did. :-)

And, although I would have never expected neither me nor some of my friends exhibit a similar reaction, we were in fact all somehow high, and strangely happy for the two big thermometers finally flying in the sky.

They say Planck is super-cool.
The coolest thing in the universe.
Literally.
Well, almost.
Well, only for a year.

Well, whatever. Once a geek, always a geek.

In the previous post, I promised to write more about Planck and what it's going to probe, the CMB. Which is great, and cool, yay! However, I'm also *pretty* busy with something else, just this little thing, you know... my phd defense... so sorry, Planck high or not, I'm clearly busy. Busy freaking out.

But don't despair! I delegated the explanation of the mysteries of the universe that will be unravelled by Planck to my friend and colleague Bjoern, who happens to be a much more respected authority than myself, mainly about everything, and in the specific case, about the CMB, of course --> see next post.

Image: abridged from Andy Riley, The Book of Bunny Suicides.
Credits: well, my friends :-)

Disclaimer: the US flag is not supposed to be there!!! Planck is not a US mission, but mostly European (ESA)!!!

We decline responsabilities.
It's a poetic licence.
Please, forgive us.
Turns out, we're not that geek, after all.

surprise surprise!

2009-05-04T20:36:00.010+02:00

as this picture shows, the (visible) light that we see with our own eyes is just a teeny tiny portion of what is called the electromagnetic spectrum:

the picture actually comes from a t-shirt (but if you happen to land on that page, please do not read any of the comments, they're all wrong!!!) but the designer borrowed the idea from a science book, so it's pretty useful. look at the names above: don't they evoke any memories?? gamma rays, x-rays, ultra-violet, infra-red, microwave, radio... although we might relate different real-life concepts to each of them, they are basically the same thing: radiation, light, just like the one we see with our very own eyes. just, with different, very different energy, the gamma rays being the most energetic, and down all the way to the radio.

astronomical objects, such as stars, galaxies and other stuff, emit all these sorts of radiation, from gamma to radio. fortunately for us, the earth's atmosphere absorbs most of them (because they would be dangerous or even lethal to living creatures), that means that from earth we can only observe in the visible and in the radio band. yes, they are also referred as spectral bands.

but if we shoot a nice (and super expensive) satellite up into the skies, so that it orbits the earth, then we can observe in the whole spectrum, and gain a lot more information about all sorts of astronomical sources and the physical processes happening there. that's why Planck and Herschel will be launched soon (check prev post) and many other satellites are already up there doing this job.

********

beware: recently i'm reading over and over people writing that waves in other bands besides the visible are sound waves. like that we could listen to the sound of the stars. SO NOT TRUE. sound waves are one thing, electromagnetic waves (ie. light) are a totally different thing. maybe it's the "radio" word that creates confusion. maybe the word "frequency". whatever. the only difference between radio and visible and gamma rays is THEIR ENERGY!!!

don't know if i managed to be clear enough. maybe not. i'd need to get started with an intro to waves. and if you happened to be on this blog, you probably already know.

anyway: don't listen to stars - or to whatever other weird ideas crazy people have!!!

Image credits: Threadless - www.threadless.com

so cute!

2009-05-04T20:17:00.012+02:00

ok, i'm not usually this cheesy, but i really find this photo so cute!

it shows the satellite Herschel reflected in the mirror of the satellite Planck, which will (hopefully!) be launched next week, sharing the same rocket. that's why i actually found the picture totally sweet!

Herschel will observe the sky in the infrared, whereas Planck will scan it in the microwave, focussing on the CMB (cosmic microwave background), ie. the relic signature coming from the big bang.

ok, maybe it's a bit confusing... if infrared and microwave don't tell you much, check the next post for clarification. and check this blog soon for more about the CMB and Planck...

Image credits: ESA

the unbearable expansion of the universe

2009-04-23T00:19:00.016+02:00

i just realised it's exactly 80 years now that Hubble found out we live in an expanding universe. yes, the galaxies all move away from each other, just like the points in this cute vintage photo do, as space itself is expanding. but i don't know how widely known this fact actually is. sometimes people ask me "since you're an astronomer, tell me, do you believe in the big bang theory??" like if it was a choice to believe in it or not! hell yes, this is my answer! true, it was a controversial topic, but those were... the 60's!! i mean, i reckon it IS a theory, and science wouldn't go on if theories weren't to be proven wrong from time to time, but up to now, with the experimental data collected so far, there is no other competing explanation at all. sure, the expansion is probably accelerating, and whatever is driving the acceleration, we almost know anything about that. true. but the expansion is a fact. people, deal with it!!!

Image credits: Life Magazine

developing astronomy globally

2009-03-27T18:35:00.006+01:00

one of the key ideas of the International Year of Astronomy is to point out the contribution of astronomy to development.

in this context, it has just been announced that there will be grants available for projects related to the development of astronomy all over the world, especially in those regions that do not already have strong astronomical communities.

i thought it's an interesting opportunity, although i have no particular idea in mind and i have no experience whatsoever in planning such a project. so i thought i'd advertise it, at least...

the grants amount to 1,000 euro each, and the call for proposals can be found at the following address:

www.developingastronomy.org

Deadline: April 3rd, 2009
Watch out: deadline is next week!!!!

Note that, although this funding is aimed specifically at "developing countries", exceptions with appropriate motivation will be accepted - the main concern simply being who the beneficiaries would be.

Into the clouds where stars are born

2009-03-26T00:00:00.014+01:00

Looking at the sky in the daytime, weather permitting, it is possible to see the Sun, the star which provides us with light and heat, thus making life on Earth possible. Looking at the sky during the night, one can see millions of stars: the firmament is abundant in large and small suns, located here and there in our galaxy, the Milky Way. Looking further away, with the aid of a binocular or a telescope, it is possible to perceive other galaxies, each of them containing from tens of millions to hundreds of billions of stars. Stars, stars, and even more stars. Where do all these stars come from? How did they form? They all derive from a mixture of gas and dust, known as interstellar medium, which is another important component of galaxies. The interstellar medium is rather homogeneous, but regions occur where the gas is particularly dense: it is exactly in these clouds, or nebulae, that stars are born.

When the gas within a nebula is so dense that its pressure cannot balance its own weight, the so-called gravitational collapse begins: the cloud starts breaking down into small fragments, which keep contracting and become rotating spheres of gas, increasingly denser and hotter. Collapse continues for a long time (up to a million years), until the temperature achieved within each “sphere” is so high that nuclear reactions set it, turning hydrogen into helium and producing energy: the gas “sphere” has now become a star. From the collapse of a single nebula, hundreds to thousands of stars with different masses are formed: the most massive ones will only live a few million years, whereas the smallest ones will go on burning for billions, even hundred billions of years.

This image of the Eagle Nebula is an example of a “stellar nursery”: the elongated structures visible in the centre are huge pillars of gas and dust, larger than our own Solar System, where stars are born. The bluish light permeating the central regions of the nebula comes from the first, young stars which formed: with their energy, they heat up the surrounding gas, thus making the formation of new stars even more likely. This image, obtained with the telescope on Kitt Peak in Arizona, USA, has an extremely high resolution, which allows to study star formation in detail; however, the Eagle Nebula can be observed even with a binocular, in the constellation of the Serpent, visible from Europe from May to September. New stars are formed all the time: in order to see them, we only need to lift our eyes up to the sky.

In the image, the Eagle Nebula, an open window onto the processes of star formation. Credits: T. A. Rector & B. A. Wolpa, NOAO, AURA.

Translated from Il Denaro, 12.02.2009

In search of the ideal site for astronomy

2009-01-28T00:12:00.016+01:00

or: why is it convenient to build observatories on a volcanic island or a desertic plateau?

One fifth of the world population can no longer enjoy the sight of the night sky with the naked eye: close to urban and industrial areas, light pollution allows one to see only a few stars. It is a well known fact: anyone can perceive it, whenever looking up to the sky. If asked “which is the ideal site for astronomy?”, many would answer “far away from big cities.” Right, but not enough. Because escaping from light pollution is not the only problem to handle, in this case.

The key instrument in astronomy is the telescope. As the name itself says, its purpose is to look at objects which are located far away. In order to observe distant stars and galaxies, a telescope has to catch as much light as possible: this means that very large mirrors (currently with diameters of order 10 m, but up to 100 m for future generations) and very long exposure times are needed to achieve a good image. Unfortunately, before reaching the telescope, the light rays coming from stars and galaxies have to pass through the atmosphere of the Earth. Here, the cosmic light interacts with the turbulent atmosphere, thus losing track of much information about the objects (stars or galaxies) it comes from.

The atmosphere is not static nor homogeneous, but extremely turbulent. At every instant, a star or galaxy produces a slightly different image, according to the varying characteristics of the portion of atmosphere overlooking the telescope. A long exposure, needed to capture as much light as possible, is a superposition of the individual images obtained in several, consecutive instants. Because of atmospheric turbulence, the image resulting from such a superposition is blurred: this phenomenon is referred to as seeing.

It goes without saying that modern astronomy needs accurate and precise images, and the limiting effects due to the atmosphere have to be taken under control. Hence, in the last decades telescopes are being built in dry regions, preferably at high altitude, close to oceans or deserts, so that the surrounding air temperature is as constant as possible and the turbulence minimal. This is the reason why the ideal sites to build cutting-edge astronomical observatories are volcanic islands, such as Hawaii or the Canary Islands, and desertic plateaux, such as the Atacama desert in Chile.

An even more radical solution to remove the effect of seeing is a telescope orbiting around the Earth, outside of the atmosphere: though rather expensive, this formula has already been pioneered with the Hubble Space Telescope, and is the subject of several projects for the upcoming future.

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The photo, taken by Bobb Tubbs, shows the European telescopes in La Palma, on the Canary Islands: at an altitude of over 2,400 m, the observatory is higher than the clouds and the seeing is one of the best in the world.

Translated from Il Denaro, 22.01.2009

happy year of astronomy!

2009-01-15T00:22:00.007+01:00

well, this blog didn't turn out to be a great success, i didn't really write a lot and stuff... lack of time, lack of ideas. whatever. the science magazine exercise idea was probably too ambitious, time-demanding, whatever...
but this year's the international year of astronomy, so i'll try to blog more, at least about astro stuff...

and if you want to celebrate the year of astronomy, visit www.astronomy2009.org and enjoy it :)

Energy comes from dancing!

2008-12-22T03:33:00.007+01:00

last weekend i organised an anti-xmas-stress party (check the poster out: i made it! and am so proud of it!) with some people from the Weltladen, the fair trade store here in Heidelberg, and the dj there told me about a brand new club in the Netherlands where they are trying to use sustainable technologies, like that they produce electricity from the energy of the people dancing... how cool is that?? i was super excited, as i am always whenever i hear about energy that is conserved and reused in a clever way, and not only dissipated! so i started looking for info about the whole business, and i found out a lot of stuff...

the club is called Watt, it opened 3 months ago in Rotterdam and it's the first sustainable dance club ever. first, there is a special dance floor which makes use of the piezoelectric effect: some elements, crystals like quartz, if deformed or compressed are able to develop a potential difference, which can be plugged into a circuit and directly transformed into electric energy! which means that the more the people dance in the club, ie. the better the party is, the more energy is produced, and you can directly see it in the light show of the club itself! it clearly has a tiny energetic efficiency, but still it raises awareness about energetic issues, plus the club is sustainable in so many other aspects, from the refillable cups to the spectacular toilet where the flush water comes directly from the rain collected on the roof... for more info check out the website of the company (Sustainable Dance Club) or - if you trust me! - this article i recently wrote (in Italian...)

and now i want to go there and have a look, dance it out, produce some positive energy - and maybe take it along with me, i feel i need some...

Image credits: Mike Nolte & Giulia Melloni

when pluto was a planet

2008-11-13T03:42:00.010+01:00

or, the age of innocence from an astronomer's point of view

for 76 years, kids in school have learned that our solar system has 9 planets: mercury, venus, the earth, mars, jupiter, saturn, uranus, neptune and pluto. first the four "rocky" ones, small and made out of solid material. then the four "giant" ones, much more massive and made out of a dense mixture of gaseous elements. and then, there was pluto.

pluto was the last one to be discovered, in 1930, and has always had the charm of an outsider. it is the farthest of the sun's court, but not always: its orbit is in fact very eccentric, and crosses the one of neptune, so that the two switch regularly in being the most distant from the sun. another weird fact about pluto is that it is rocky and tiny, like the earth-like planets, and unlike its closer, giant neighbours.

when pluto was still a planet, it also had a satellite, charon. charon was identified as a satellite only because it had been discovered more than 40 years later after pluto, but it would have been more appropriate to refer to them as a double planet system: contrarily as for all other satellites, the mass of charon is not significantly smaller than that of pluto.

then, the past decade witnessed new discoveries: quaoar, sedna and eris, all objects with masses and orbits very similar to pluto's. who knows how many other pluto-like bodies future observations will report. not being able to ignore the new discoveries, but also trying to prevent the number of solar system planets to increase dramatically, the international astronomical union called a halt and came out with an official definition for a planet.

the new definition involves not only being a celestial body orbiting the sun with a nearly spherical shape, but also being the object which contains most of the mass in its own orbit.
not being much larger than its fellow charon, pluto did not fulfill the definition, thus ceased being a planet in 2006.

i grew up with the dream of becoming an astronomer, thinking that the practice of such a pure science was the highest step of human knowledge. not that it mattered much, but at the time i was also aware that i was living in a special planet out of a set of nine. then i started moving my first steps in the world of astronomy and astrophysics, still amazed by the idea of research. i was walking along the twilight zone, uncertain about how to cross it, and suddenly pluto was not a planet anymore. reality was there to be faced: science was no more the purest of all things, it is in fact just a human matter. it was not as neat as i thought, but most importantly i learned how it isolates the individuals who practice it from the rest of the world. i started wondering if this price is worth the game. and i'm still wondering. the age of disillusion.

right after the end of pluto's career as a planet, the american dialect society chose "to pluto" as word of the year. it's supposed to mean "to deprive something of its value". along with the former ninth planet, also my dream was plutoed. but i decided to restore its value. i realised science was not what i had expected, but i chose to deal with it, to adjust my dream and take the most i could from it. pluto is now a dwarf planet. let's see what happens to me and science.

a science blog

2008-10-13T04:15:00.006+02:00

here's a new blog. it's supposed to be a container of all my writing attempts, which are going to be more or less related to science.
scientific topics, science teaching, science and society. whatever.
and since i like to make things difficult, each time i'm going to choose a topic and write something in the style of some specific magazine.
let's see how long it lasts...