Hubble's birthday and a contest

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

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

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.

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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

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.

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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.