RSSArchive for April, 2011

A rovin’ on Mars

WHEN NASA’S MARS ROVER Opportunity touched down on the Red Planet on January 25, 2004—three weeks after its twin, Spirit, landed—the official requirement was that it would need to last 90 days to give scientists enough time to do their most important investigations.

Well, it’s now more than seven years later and the plucky rover shows no signs of giving up.

Having travelled more than 27 kilometres at an average speed of around 36 metres per hour, Opportunity has explored many and varied places near its landing site on Meridiani Planum.

For the past couple of years, it has been slowly making its way toward its new destination, Endeavour Crater—a 22-kilometre-wide impact crater that scientists want to investigate. Most recently, Opportunity has been near Santa Maria crater—see our earlier story—and has another six kilometres to go before it reaches Endeavour.

The video above (which doesn’t have any audio) is courtesy of NASA, and shows just how far the intrepid little rover travelled between January 2004 and January 2011.

Adapted from information issued by NASA / JPL.

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Wrinkles on the Moon

LROC image of Brisbane Z crater

A 'wrinkle ridge' splits the crater known as Brisbane Z, located in the Mare Australe region of the Moon. Image width is 100 kilometres. The region within the white box is shown in detail in the image below.

A WRINKLE RIDGE SEEMS TO DIVIDE the crater Brisbane Z in half. Brisbane Z is a mare-flooded crater within the Mare Australe region of the Moon.

Wrinkle ridges are one of several styles of tectonic deformation present on the Moon, and occur primarily in the maria, or lunar ‘seas’.

Wrinkle ridges are the result of contractional forces, and in the maria, these forces are believed to be from the weight of the basalts poured onto the surface by volcanic activity billions of years ago.

The same reasoning explains why wrinkle ridges are sometimes found in magma-flooded craters, where similar contractional forces are present at a smaller scale.

Close-up view of Brisbane Z's wrinkle ridge

A Lunar Reconnaissance Orbiter Camera close-up image of the terrain on Brisbane Z's wrinkle ridge. Image width is 500 metres.

Adapted from information issued by LRO Team / NASA / GSFC / Arizona State University.

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The outer limits

Hubble image of distant galaxy

Earlier this year, the Hubble Space Telescope spotted what could be the farthest and one of the very earliest galaxies ever seen in the universe so far. This is the deepest infrared image taken of the universe (deeper even than the Hubble Deep Field; see image below). Based on the galaxy's colour, astronomers believe it is a staggering 13.2 billion light-years away.

HOW FAR CAN WE SEE into the cosmos? And what lies beyond what we can see? Will we ever know what exists beyond the ‘edge of space’?

These questions were posed recently by SpaceInfo readers in response to our story on what astronomers will see one trillion years from now.

They’re very interesting questions indeed. The answers require a bit of thought, and especially they require someone who knows what they’re talking about and can provide them in an understandable manner.

Dr Tamara Davis

Dr Tamara Davis

Introducing Dr Tamara Davis, a cosmologist and Research Fellow in the Physics Department at the University of Queensland. Tamara is involved in some of the most exciting cosmological research going at the moment, and her achievements were recognised a couple of years ago when she was honoured with the 2009 L’Oréal Women in Science Award.

We’re grateful to Tamara for taking the time to give us the following brief explanation of how far we can see, how far we might be able to see in the future, and why there are some things we’ll never see.

Our cosmic Horizons

by Dr Tamara Davis, University of Queensland

SpaceInfo readers have asked about what lies beyond the reach of our view of the cosmos. This is a great question, and I hope the following explanation will help everyone to understand the situation.

There are actually two types of ‘cosmic horizon’. There’s a limit to how far we can see right now, and a different limit to how far we’ll be able to see in the far future.

The limit to how far we can see right now is called our “particle horizon” because it is the distance to the most far-away “particle” (eg. galaxy) that we can currently see.

The particle horizon arises because light has been able to travel only a finite distance since the Big Bang. If we had been around to shine a light from our position at the time of the Big Bang, then the distance that light could have travelled by now is the distance to our particle horizon.

This kind of horizon is getting bigger as time goes on (as light has more time to travel), and we’re continually able to see things further and further away (and further and further back in time).

Practically speaking, we can’t actually see all the way to our theoretical particle horizon because to do so we’d have to see light that was emitted right at the moment of the Big Bang. The universe was so dense back then that light couldn’t travel very far before getting scattered. It was unable to ‘break out’ from the dense cosmic ‘soup’.

In practical terms the most distant thing we can see is what cosmologists call the “last scattering surface”. This was the state of play about 100,000 years after the Big Bang, when the universe’s density dropped to the point that light could break out and travel relatively unimpeded.

These days we perceive that light as a uniform glow of microwave radiation from all directions, known as the cosmic microwave background. Some of the static picked up by old analogue TVs came from this radiation … so, funnily enough, when you saw fuzz on your TV screen you were actually detecting light from our effective particle horizon!

Hubble Deep Field

The Hubble Deep Field is one of the iconic images of space, showing us galaxies into the far distant universe. And the further away a galaxy is, the further back in time we're seeing it.

Edge of the great unknown

The other type of horizon, probably more relevant to the discussion in the original article, is our “event horizon”, which is the limit to how far we will be able to see in the infinite future.

If we were to shine a light outwards from our position now, then the distance it can travel in the future is our event horizon.

Now, you might think that, unless the cosmos were to somehow end, a light beam could travel an infinite distance into an infinite future. But in a universe whose rate of expansion is accelerating (like ours) that isn’t true, so there’s a limit to how far we will be able to see, even given infinite time.

This is because there are distant parts of the universe expanding away from us faster than the speed of light… the only way light from galaxies in the most distant reaches of the universe can reach us is if the universe’s expansion slows down.

It’s a bit like a swimmer caught in a rip, trying to swim back to shore…she can’t swim faster than the rip, so she’ll never make it. Unless the rip slows down she hasn’t got a chance.

But our universe is not slowing down, the expansion is actually speeding up, so light from some distant galaxies will forever be out of view.

This limit is called our “event horizon” because it separates events we will be able to see from events we will never be able to see.

The event horizon is actually a more stringent limit than the particle horizon, because not only do you have to ask whether you can see the particle, but also if you can see it for its entire life.

Many galaxies that we can currently see are actually, by now, well beyond our event horizon—because although we can see them as they were in the past, we will never be able to see them as they are today.

Our current event horizon is at a redshift of 1.8…that’s about 5 giga-parsecs away. (A giga-parsec is one billion parsecs, with a parsec being 3.26 light-years.)

You might have seen the Hubble Deep Field (see image above)—one of the ‘deepest,’ most detailed photos of the universe ever taken. The most distant galaxy in that image is beyond a redshift of 6 (more than 8 giga-parsecs away).

That means that a huge number of the galaxies we can see in that image are now actually beyond our event horizon. The Hubble Deep Field shows us a snapshot of them as they were in the past, but we’ll never be able to communicate with them.

More information

For more information about this subject, and for some scientific diagrams of how far we can see in the universe, you can download a fascinating PDF-format article by Tamara from

She’s also written another great article that helps straighten out this wide topic, “Misconceptions about the Big Bang” (Scientific American, March 2005). And for even more information you can visit her website at

Distant galaxy image courtesy NASA, ESA, Garth Illingworth (UC Santa Cruz), Rychard Bouwens (UC Santa Cruz and Leiden University) and the HUDF09 Team / A. Feild (STScI). HDF image courtesy R. Williams (STScI), the Hubble Deep Field Team and NASA. Tamara Davis image courtesy / Science in Public.

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A year in the Sun

APRIL 21, 2011 MARKED the one-year anniversary of the Solar Dynamics Observatory (SDO) First Light press conference, where NASA revealed the first images taken by the spacecraft.

In the last year, the Sun has gone from its quietest period in years to the activity marking the beginning of solar cycle 24. SDO has captured every moment with a level of detail never-before possible.

The mission has returned unprecedented images of solar flares, eruptions of prominences, and the early stages of coronal mass ejections (CMEs).

In this short video are some of the most beautiful, interesting, and mesmerising events seen by SDO during its first year.

Adapted from information issued by NASA GSFC.

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Close encounter of the galactic kind

Galaxies NGC 3169 (left) and NGC 3166

Galaxies NGC 3169 (left) and NGC 3166 (right) are close enough together to feel each other's distorting gravitational influence. The tug-of-war has warped the spiral shape of NGC 3169, and fragmented the dust lanes in NGC 3166.

  • Galaxies NGC 3169 and 3166 are 70 million light-years from Earth
  • They’re close enough together to be warped by each other’s gravity

THE GALAXIES IN THIS COSMIC PAIRING, captured by the Wide Field Imager on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile, display some curious features, demonstrating that each member of the duo is close enough to feel the distorting gravitational influence of the other.

The gravitational tug-of-war has warped the spiral shape of one galaxy, NGC 3169 (on the left), and fragmented the dust lanes in its companion, NGC 3166.

Meanwhile, a third, smaller galaxy to the lower right, NGC 3165, has a front-row seat to the gravitational twisting and pulling of its bigger neighbours.

This galactic grouping—located about 70 million light-years away in the direction of the constellation Sextans (The Sextant)—was discovered by the English astronomer William Herschel in 1783.

Modern astronomers have gauged the distance between NGC 3169 (left) and NGC 3166 (right) as a mere 50,000 light-years. That’s only about half the width of our Milky Way galaxy.

In such tight quarters, gravity can start to play havoc with galactic structure.

Mostly ‘armless

Spiral galaxies like NGC 3169 and NGC 3166 tend to have orderly swirls of stars and dust pinwheeling about their glowing centres. Close encounters with other big galaxies can jumble this configuration, often serving as a prelude to the merging of the galaxies into one larger galaxy.

So far, the interactions of NGC 3169 and NGC 3166 have just lent a bit of character. NGC 3169’s arms, shining bright with big, young, blue stars, have been teased apart, and lots of luminous gas has been drawn out from the main body.

In NGC 3166’s case, the dust lanes that also usually outline spiral arms are in disarray. The lack of blue colour indicates that NGC 3166 is not forming many new stars.

Galaxy NGC 3169 with supernova

Galaxy NGC 3169 with supernova SN 2003cg marked.

Spotting a supernova

NGC 3169 has another distinction—the faint yellow dot beaming through a veil of dark dust just to the left of and close to the galaxy’s centre. This flash is the leftover of a supernova detected in 2003 and known accordingly as SN 2003cg. (Note that this supernova does not still shine today—the image was taken back in 2003.)

A supernova of this variety, classified as a Type Ia, is thought to occur when a dense, hot star called a white dwarf—a remnant of medium-sized stars like our Sun—gravitationally sucks gas away from a nearby companion star.

This added fuel will eventually cause the whole star to explode in a runaway nuclear fusion reaction.

The new image presented here of a remarkable galactic dynamic duo is based on data selected by Igor Chekalin for ESO’s Hidden Treasures 2010 astrophotography competition. Chekalin won the first overall prize and this image received the second highest ranking of the nearly 100 contest entries.

Adapted from information issued by ESO / Igor Chekalin.

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Runaway star shocks the neighbours

WISE view of Zeta Ophiuchi

The star Zeta Ophiuchi (image centre) is surrounded by a cloud of dust and gas in this view from NASA's WISE infrared space telescope. The star is zooming from right to left at 87,000 kilometres per hour, forming a bow shock in the cloud in front of it.

THE BLUE STAR NEAR THE CENTRE of this image is called Zeta Ophiuchi. When seen at visible light wavelengths it looks like a relatively dim red star surrounded by other dim stars and no dust.

However, in this infrared image taken with NASA’s Wide-field Infrared Survey Explorer, or WISE, a completely different view emerges.

Zeta Ophiuchi is actually a very massive, hot, bright blue star ploughing its way through a large cloud of interstellar dust and gas.

Astronomers think this stellar juggernaut was once part of a binary star system with an even more massive partner. It’s believed that when the partner exploded as a supernova, blasting away most of its mass, Zeta Ophiuchi was suddenly freed from its partner’s pull and shot away like a bullet, moving 24 kilometres per second (87,000 kilometres per hour).

Zeta Ophiuchi is about 20 times more massive and 65,000 times more luminous than the Sun. If it weren’t surrounded by so much dust, it would be one of the brightest stars in the sky and appear blue to the eye.

Like all stars with this kind of extreme mass and power, it subscribes to the ‘live fast, die young’ motto. It’s already about halfway through its very short 8-million-year lifespan.

Artist's impression of WISE

Artist's impression of NASA's WISE space telescope, which studies the cosmos at infrared wavelengths.

In comparison, the Sun is roughly halfway through its 10-billion-year lifespan.

While the Sun will eventually become a quiet white dwarf, Zeta Ophiuchi, like its ex-partner, will ultimately die in a massive explosion called a supernova.

Perhaps the most interesting features in this image are related to the interstellar gas and dust that surrounds Zeta Ophiuchi. Off to the sides of the image and in the background are relatively calm clouds of dust, appearing green and wispy.

Near Zeta Ophiuchi, these clouds look quite different. The cloud in all directions around the star is brighter and redder, because the extreme amounts of ultraviolet radiation emitted by the star are heating the cloud, causing it to glow more brightly in the infrared than usual.

Even more striking, however, is the bright yellow curved feature directly above Zeta Ophiuchi. This is a magnificent example of a bow shock. The runaway star is flying from the lower right towards the upper left. As it does so, its very powerful stellar wind is pushing the gas and dust out of its way, forming an invisible ‘bubble’ all around it.

Directly in front of the star’s path the wind is compressing the gas together so much that it makes it glow extremely brightly (in the infrared).

Adapted from information issued by NASA / JPL-Caltech / UCLA / IPAC.

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Hubble’s 21st anniversary image

Galaxy pair Arp 273

Hubble image of galaxy pair Arp 273. The distorted shape of the larger galaxy indicates that the smaller galaxy has actually passed through the larger one some time in the past.

THE HUBBLE SPACE TELESCOPE turns 21 today, and astronomers have celebrated by pointing it at an especially photogenic pair of interacting galaxies that together are called Arp 273.

The larger of the spiral galaxies, known as UGC 1810, has a main body that is distorted into a rose-like shape by the gravitational pull of the companion galaxy below it, known as UGC 1813.

The swathe of blue jewels across the top of UGC 1810 is the combined light from clusters of intensely bright and hot, young, blue stars. These massive stars glow fiercely in ultraviolet light.

The smaller, nearly edge-on galaxy UGC 1813 shows distinct signs of intense star formation at its core, perhaps triggered by the encounter with UGC 1810.

A series of uncommon spiral patterns in UGC 1810 are a telltale sign of a close encounter between galaxies. The large, outer arm forms a partial ring around the galaxy, a feature that is seen when two galaxies actually pass through one another. This suggests that the smaller galaxy actually ‘dived’ deeply, but off-centre, through UGC 1810.

The inner set of spiral arms is highly warped out of the flat plane of the galaxy, with one of the arms going behind the bulge and coming back out the other side. How these two spiral patterns connect is still not precisely known.

The image also shows a tenuous tidal bridge of gas between the two galaxies, which are separated by tens of thousands of light-years from each other.

Download a screen wallpaper size (1280 x 1024) version of the image here.

UGC 1810 has a mass about five times that of UGC 1813. In unequal pairs such as this, the relatively rapid passage of the smaller galaxy produces the lopsided structure in the big galaxy.

Also in such encounters, starburst activity typically begins earlier in the minor galaxy than in the major galaxy. This could be because to the fact that the smaller galaxy has consumed less of the gas present in its core, from which new stars are born.

The Arp 273 pair is roughly 300 million light-years from Earth.

Adapted from information issued by HEIC. Image courtesy NASA, ESA and the Hubble Heritage Team (STScI/AURA).

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Squished stars have researchers in a spin

Zoomed-in view of the star Regulus

A "zoomed in" view of the star Regulus. Measurements of the temperature of the star's poles and equator have shown up flaws in a century-old astronomical theory about hot, fast-spinning stars.

  • Hot stars spin so fast that they become slightly flattened
  • Theory predicts temperature differences between poles and equator
  • New measurements show the theory has major flaws

THE HOTTEST STARS IN THE UNIVERSE spin so quickly that they become a bit squished at their poles and dimmer around their middle.

But the 90-year-old theory that predicts the extent of this “gravity darkening” phenomenon has major flaws, according to a new study led by University of Michigan (U-M) astronomers.

The von Zeipel law, named for its creator Swedish astronomer Edvard Hugo von Zeipel, has been used for the better part of a century to predict the difference in surface gravity, brightness and temperature between a rapidly rotating star’s poles and its equator.

Using a technique called interferometry, the U-M researchers essentially ‘zoomed in’ to take close-up pictures and measurements of the giant star Regulus.

If Regulus were spinning just a few percent faster, it would fly apart.

The astronomers found that the actual difference in temperature between its equator and poles is much less than the old theory predicts.

Measurements don’t match the theory

“It is surprising to me that von Zeipel’s law has been adopted in astronomy for such a long time with so little solid observational evidence,” said Xiao Che, a doctoral student in the Department of Astronomy who is first author of a paper on the findings to be published in Astrophysical Journal on April 20.

It’s important to get the numbers right, says John Monnier, an associate professor in the U-M Department of Astronomy.

“In some cases, we found a 5,000-degree Fahrenheit [2,750 degrees Celsius] difference between what the theory predicts and what our actual measurements show,” Monnier said.

CHARA telescope array

Combining the light from the six CHARA telescopes (arrowed) with the Michigan Infra-Red Combiner, gives astronomers a virtual telescope 100 times as big as the Hubble Space Telescope.

“That has a big effect on total luminosity. If we don’t take this into account, we get the star’s mass and age and total energy output wrong.”

Zooming in with virtual telescope

Monnier led the creation of the Michigan Infra-Red Combiner (MIRC) instrument that was used to take the measurements. MIRC combines the light from four telescopes at the CHARA array at Georgia State University, producing a virtual telescope 100 times larger than the Hubble Space Telescope.

This interferometry technique enables astronomers see the shape and surface characteristics of stars. Without this technique, stars look like mere points of light even through the largest telescopes.

In this case, zooming in on Regulus let the researchers measure its poles and equator temperatures separately.

“Normally, you would just be able to get an average temperature,” Monnier said.

So where did von Zeipel go wrong? Monnier believes his Swedish predecessor didn’t take into account circulation patterns on stars that are not unlike wind patterns on Earth.

“The Earth has a hot equator and cold poles and that causes air circulation,” Monnier said.

“The hot air wants to flow toward the poles and equilibrate, bringing the temperatures closer together. This is a source of some weather patterns on Earth.”

Adapted from information issued by the University of Michigan. Regular image courtesy Xiao Che.

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Orion’s hidden dimensions

WISE view of part of Orion

An infrared view of the region around The Hunter's head in the constellation Orion, taken by NASA's WISE infrared space telescope. The bright star at lower left is Betelguese.

IN GREEK MYTHOLOGY, Orion was a hunter whose vanity was so great that he angered the goddess Artemis. As his punishment, Artemis banished the hunter to the sky where he can be seen as the famous constellation Orion.

In the constellation, Orion’s head is represented by the star Lambda Orionis. When viewed in infrared light, NASA’s Wide-field Infrared Survey Explorer, or WISE, reveals a giant nebula around Lambda Orionis, inflating Orion’s head to huge proportions.

Lambda Orionis (1,060 light-years from Earth) is a hot, massive star that is surrounded by several other hot, massive stars, all of which are creating radiation that excites a ring of dust, creating the ‘Lambda Orionis molecular ring’.

Also known as SH 2-264, the Lambda Orionis molecular ring is sometimes called the Meissa ring. In Arabic, the star Lambda Orionis is known as ‘Meissa’ or ‘Al-Maisan,’ meaning ‘the shining one’. It is 1,470 light-years from Earth.

The Meissa Ring is of interest to astronomers because it contains clusters of young stars and proto-stars, or forming stars, embedded within the clouds.

With a diameter of approximately 130 light-years, the Lambda Orionis molecular ring is notable for being one of the largest star-forming regions WISE has seen.

This is also the largest single image featured by WISE so far, with an area of the sky approximately 10 by 10 degrees in size; equivalent to a grid of 20 by 20 full Moons.  Nevertheless, at less than 1 percent of the whole sky’s area, it is just a taste of WISE data.

Close up WISE view of Betelguese

Betelgeuse is a red supergiant star, approximately 600 light-years from Earth. It looks blue in this infrared view.

The Hunter’s female warrior friend

The bright blue star in the lower left corner of the image is Betelgeuse, which represents one shoulder of the hunter Orion. The name Betelgeuse is actually a corruption of the original Arabic phrase ‘Yad al-Jauza’ meaning ‘hand of the giant one’.

Betelgeuse (roughly 600 light-years from Earth) is well known for being a red supergiant star, yet in WISE’s infrared view it appears blue, as do most stars in WISE images. This is because most stars, including Betelgeuse, put out more light in the shortest infrared wavelengths of light captured by WISE, and those shorter wavelengths are presented in WISE images as blue and cyan.

In visible light, Orion’s other shoulder is clearly marked by the variable star Bellatrix (400 light-years from Earth). In infrared light, however, Bellatrix is a somewhat unremarkable cyan-coloured star in the right side of the image.

In Latin, Bellatrix means ‘female warrior,’ which is perhaps why the name was chosen for a female witch character in the popular Harry Potter books.

Also seen in this image are two dark nebulae, Barnard 30 and Barnard 35, which are parts of the Meissa ring that are so dense they block out visible light. Barnard 30 is the bright knob of gas and dust in the top centre part of the image. Barnard 35 appears as a hook extending towards the centre of the ring just above and to the right of the star Betelgeuse.

The bright reddish object seen to in the middle right part of the image is the star HR 1763, which is surrounded by another star-forming region, LBN 876.

Download a full-size (1.83M, 1600 x 1489 pixel) image here.

Adapted from information issued by NASA / JPL-Caltech / WISE Team.

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Pluto has a CO glow

Artist's impression of Pluto and Charon

An artist's impression of Pluto and its largest moon, Charon. Astronomers have detected thin traces of carbon monoxide gas in the dwarf planet's atmosphere.

ASTRONOMERS HAVE DISCOVERED carbon monoxide in the atmosphere of Pluto, capping off nearly two decades of work to detect the gas in the ‘air’ of the distant, icy world.

Pluto, discovered in 1930, was long considered the Sun’s smallest and most distant planet. Since 2006, though, it has been regarded by many astronomers as a ‘dwarf planet’…one of a handful of such bodies with sizes of hundreds of kilometres that orbit in the distant reaches of the Solar System, out beyond Neptune.

Pluto is the only dwarf planet known to have an atmosphere. The thin layer of gases was detected in 1988 when it dimmed the light of a distant star as Pluto passed in front of it.

The new results, obtained using the 15-metre James Clerk Maxwell Telescope in Hawaii, show a strong signal of carbon monoxide gas.

Team leader Dr Jane Greaves of the University of St Andrews will present the new discovery today at the UK National Astronomy Meeting in Wales.

Fragile atmosphere

Previously, Pluto’s atmosphere was known to be over a hundred kilometres thick, but the new data raise this height to more than 3,000 kilometres—a quarter of the way out to Pluto’s largest moon, Charon.

In 1989 Pluto made its closest approach to the Sun, a comparatively recent event given that it takes 248 years to complete each orbit. The gases probably result from solar heating of surface ice, which sublimates (goes directly from ice to gas) as a consequence of the slightly higher temperatures during this period.

The resulting atmosphere is probably the most fragile in the Solar System, with the top layers blowing away into space.

“The height to which we see the carbon monoxide agrees well with models of how the solar wind strips Pluto’s atmosphere,” commented team member Dr Christiane Helling, also of the University of St Andrews.

Artist's impression of the view from the surface of Pluto

Artist's impression of the view from the surface of Pluto, showing a thin, hazy atmosphere.

Deep space cold snap

The gas is extremely cold, about -220 degrees Celsius. A big surprise for the team was that the CO measurement was more than twice as strong as an upper limit obtained by another group, who used the IRAM 30-metre telescope in Spain in 2000.

“It was thrilling to see the signal gradually emerge as we added in many nights of data”, said Dr Jane Greaves, the team leader from the University of St Andrews.

“The change in brightness over the last decade is startling,” she added. “We think the atmosphere may have grown in size, or the carbon monoxide abundance may have been boosted.”

Such changes have been seen with Pluto before, but only in the lower atmosphere, where methane—the only other gas ever positively identified—has also been seen to vary.

Critical balance

Unlike the greenhouse gas carbon dioxide, carbon monoxide acts as a coolant, while methane absorbs sunlight and so produces heating. The balance between the two gases—which are just trace elements in what is thought to be a nitrogen-dominated atmosphere—is critical for its fate during the many-decades long seasons.

The newly discovered carbon monoxide may hold the key to slowing the loss of Pluto’s atmosphere. But if the chilling effect is too great, it could result in nitrogen snowfalls and all the gases freezing back onto the ground.

“Seeing such an example of extra-terrestrial climate-change is fascinating”, says Dr Greaves. “This cold, simple atmosphere that is strongly driven by the heat from the Sun could give us important clues to how some of the basic physics works, and act as a contrasting test-bed to help us better understand the Earth’s atmosphere.”

The JCMT is operated jointly by the UK, Canada and the Netherlands and is approaching its twenty-fifth anniversary.

The team has another Pluto observing run scheduled at the JCMT for the end of April, and in the long-term, they hope to continue tracking the changes in the atmosphere at least up to the fly-by of NASA’s New Horizons space probe in 2015.

Adapted from information issued by RAS. Images courtesy ESO / L. Calcada.

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