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.

my first proper freelance story!

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

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

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...

... 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

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.

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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!