A team of Harvard researchers has upped the ante in the race to discover the true nature of dark matter.

In a new paper posted online this week, the team says NASA’s Fermi satellite has confirmed the existence of a vast cloud of energetic electrons surrounding the center of our galaxy — electrons, they suggest, which could be subatomic shrapnel from dark matter particles colliding with one another.

If correct, their interpretation of the Fermi data would tie together a number of hints and puzzling observations that suggest dark matter is making itself visible through a process of annihilation. It also implies the existence of a new force to which only dark matter particles are attuned.

“It’s very easy to produce this kind of a signal with dark matter,” says Doug Finkbeiner of the Harvard-Smithsonian Center for Astrophysics, who led the analysis with Greg Dobler and others. “It’s not so easy to do it with other things.”

In contrast, scientists involved in gathering and analyzing the Fermi data have expressed caution over the claim. “While this work is certainly interesting, it’s premature to draw any conclusions, especially if it requires exotic physics models.” says Simona Murgia, a Stanford University physicist and Fermi science team member.

The new result is the latest twist in a story that began in 2004, when Finkbeiner reported the existence of an unexplained “haze” of microwave emission around the center of the galaxy as seen by the Wilkinson Microwave Anisotropy Probe (WMAP). He suggested then that the haze could be the mark of electrons produced when dark matter particles, thought to be concentrated near the galactic center, interact and mutually destruct.

Since then, ongoing debate over whether the haze really exists — let alone whether it’s a byproduct of dark matter — has kept the question open.

Last year, the European PAMELA satellite and a balloon-borne detector called ATIC fueled excitement by detecting, respectively, energetic positrons and electrons in greater than expected numbers in Earth’s vicinity. One possible source could be dark matter annihilations in or near the solar system, although a more conventional source, such as a nearby pulsar, could explain the excess

Fermi’s Large Area Telescope (LAT) is sensitive to both electrons and positrons, and early results discussed by team members in the spring seem to be consistent with the existence of a local excess.

Now Finkbeiner says that Fermi is also seeing a counterpart to the WMAP haze. The new result comes in the form of a diffuse glow of gamma rays around the galactic center. The properties of the gamma rays suggest they are emitted by the kind of energetic electrons expected from dark matter annihilations. Most importantly, he says, the location and distribution of the “Fermi haze” closely fits that of the WMAP haze.

Since the summer Finkbeiner has been sharing his analysis with colleagues, including the Fermi science team. The reservations they have expressed over the dark matter story stems from the basic challenge in understanding all the possible sources that could be contributing to Fermi’s overall picture of the galactic center.

“The gamma ray sky is very complex,” says Murgia. “If a signal of dark matter annihilation is there it will be mixed with other conventional components, such as gamma rays produced in cosmic ray interactions.”

For his part, says Finkbeiner, “I’m confident we’re seeing the electrons we predicted” based on WMAP.

If Finkbeiner and his colleagues are right about what Fermi is seeing, it will be harder for others to come up with convincing explanations for the haze that don’t involve dark matter.

For example the energy and smoothness of the gamma ray distribution suggests it is not the product of a single cataclysmic event, or even several discreet events, such as supernovae. Instead, the observations favor a process that generates high energy electrons throughout the galactic center on a more continuous basis.

Dark matter annihilation could account for this, because theories in which dark matter is explained by supersymmetry suggest that the lowest mass dark matter particle — also called the neutralino — is its own antiparticle. That means two neutralinos would annihilate in a flash of energy when they encounter each other, producing photons and ordinary matter particles, including electrons.

The catch is that the expected rate of annihilations should be far lower than what is needed to create the observed haze. To account for this, theorists have proposed a new force among dark matter particles that enhances the likelihood of particles meeting and boosts the expected dark matter signal.

“This has led to a nice picture where the ‘dark force’ simultaneously explains why there are so many electrons and why the annihilation rate is so high.” says co-author Neal Weiner of New York University.

The new results add to a growing sense that the identity of dark matter, a decades-old conundrum in astronomy and physics, is close to being cracked.

In addition to Fermi and related observations, researchers say efforts to detect dark matter directly in underground experiments such as XENON100 and LUX, along with the possibility that dark matter could be produced in the Large Hardron Collider, will soon narrow the range of possible explanations for the mysterious substance that accounts for 85% of the matter in the universe.

"I'm very excited about these developments," says Katherine Freese, a theoretical physicist at the University of Michigan. “It could be that a problem I’ve been working on for twenty years is on the verge of being solved.”

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Ivan Semeniuk is host of the podcast The Universe in Mind and a science journalist in residence at the Dunlap Institute for Astronomy and Astrophysics, University of Toronto.

A black hole is like a scary monster from children’s literature. It’s vividly imagined but never actually seen in real life.

This is true even for the largest black holes we know — the ones that reside at the centers of galaxies. The nearest of these lies some 30,000 light-years away, in the core of the Milky Way. If you placed it in our solar system it would probably span the orbit of Mercury. Yet, because of its great distance, it’s a mere speck against the sky, about 36 million times smaller than the full Moon. How could anyone see any detail when looking at something with an apparent size that small?

Amazingly, there is a way. And now it’s promising not only to reveal the giant black hole in our own galaxy, but also a much larger and more active one in the galaxy known as M87 in Virgo.

The nifty trick that puts this ambitious goal within reach is called very long baseline interferometry. VLBI involves two or more radio dishes that are spaced as far apart as possible — for example, in Arizona and Hawaii. The dishes observe the same radio sources in the sky, and when their signals are combined they form an image that’s as sharp as what you would get from a single receiver as big as the separation between the dishes. The idea is to show the way radio emission is spatial distributed across a small region of sky. It’s just what you need to “see” a black hole.

But what does that mean? Aren’t black holes supposed to be, well, black?

Yes and no. If completely isolated in space, a black hole would indeed be well camouflaged. But in the densely populated center of the Milky Way, there is plenty of hot gas swirling around the giant black hole there.

The energized ions in the gas give off radio waves. Seen up close, there should also be a dark sphere at the center of that swirl of gas, where matter funnels in and never comes out. The dark sphere is the infamous event horizon. It’s the point of no return, from which not even light can escape. In this case, “seeing” the black hole means seeing the event horizon silhouetted against the glowing gas.

Shep Doeleman of the Massachusetts Instistute of Technology has been leading the charge to image the Milky Way’s central black hole, and he and his collaborators have made astounding progress. They’ve looked deep into the heart of the radio source known as Sagittarius A*, where the black hole is believed to be lurking. What they’ve got is not exactly an image but a sense that there is some structure on the scale of a supermassive black hole deep in the heart of the radio source.

The complication in mapping out an image of this object is that Sgr A* is changing on a regular basis, presumably as clumps of gaseous matter go a-whirling around the black hole.

This is not going to be a problem when it comes to looking at even bigger black holes, like the giant monster at the center of the galaxy M87 in Virgo. It devours vast quantities of gas and spits out a spectacular jet that extends far into extragalactic space.

Recently, Karl Gebhardt of the University of Texas at Austin and Jens Thomas of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, set about measuring the size of M87 by running existing data through a new model that mimics the galaxy star by star. Unlike earlier efforts, their model also takes into account the unseen halo of dark matter that surround the visible portion of the galaxy. This turned out to have an unexpected affect on the way the model calculates the mass in the stars that illuminate the galaxy’s core. In the final analysis, it allocates far more mass — a whopping 6.4 billion suns — to the galaxy’s monstrous central black hole.

The surprising corollary to this is that M87’s black hole, if viewed from Earth, should be the same apparent size as the black hole in Sgr A* — just as the Sun and the Moon appear roughly the same size, though the Sun is larger and much farther way. That puts M87’s black hole within reach of Doeleman’s radio telescopes. It may even be easier to image than Sgr A* because it’s larger size means it doesn’t change nearly as rapidly.

What’s particularly exciting to theorists like Avery Broderick, of the Canadian Institute for Theoretical Astrophysics in Toronto, is that M87’s black hole is also violently active, with a vast disk of gas around it and a big jet of shooting out in one direction. A radio image of this black hole might not only reveal the event horizon but show us the region where the jet is launched.

“It’s kind of exciting as an alternate object because it is so different from the supermassive black hole in our backyard,” says Avery. “Between them, they span the range of what we expect from these objects.”

Stay tuned. Modern astronomy is increasingly become the science in which the unseen becomes seeable. Before long we’ll be adding black holes to that list.

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Ivan Semeniuk is host of the podcast The Universe in Mind and a science journalist in residence at the Dunlap Institute for Astronomy and Astrophysics, University of Toronto.

What do you do when a raging wildfire threatens to engulf your observatory? You light backfires, spray fire retardant and water bomb the slopes… but mostly you just hope for good luck.

Last month, the Mt. Wilson Observatory got a welcome dose of good luck when it escaped destruction by the notorious Station Fire, which burned out of control for weeks in the mountainous woodlands north of Los Angeles.
Mt. Wilson is home to the 100-inch Hooker telescope, one of the most storied instruments in the history of astronomy. It’s here that Edwin Hubble gathered the crucial evidence that allowed him to demonstrate, in 1925, that the universe is much, much bigger than previously thought.

In this episode of The Universe in Mind podcast, Harold McAllister, director of the Mt. Wilson Institute, talks about the observatory’s brush with oblivion. Marcia Bartusiak, author of The Day We Found the Universe explains how Hubble’s work on Mt. Wilson was the culmination of an amazing epoch of discovery that saw the cutting edge of observational astronomy migrate from Europe to the New World.

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Ivan Semeniuk is host of the podcast The Universe in Mind and a science journalist in residence at the Dunlap Institute for Astronomy and Astrophysics, University of Toronto.

Do planets around other stars have magnetic fields? It may seem an esoteric question, but life as we know it — at least terrestrial life — could not survive on Earth without the magnetic umbrella that protects us from an onslaught of hard solar radiation.

Now it appears a planet that is light years from our own may be depending on a magnetic field for its continued existence.

The planet in question is HD 209458b. Admittedly, it's more of a serial number than a name, but to astronomers it's one of the most infamous handles in the galaxy.

HD209458b caused a sensation back in 2003 when astronomers using the Hubble Space Telescope discovered a vast envelope of hydrogen gas and other atoms surrounding the planet. This was a shock because HD 209458b is also a "hot Jupiter". Although it is a gas giant planet, it is less that 1/20th the distance from its star that Earth is from the sun. At such close quarters, any gas lying beyond the planet's immediate atmosphere should quickly be torn away. Thus, the existence of a large gaseous envelope suggests a situation that is both temporary and terminal: a planet evaporating before our eyes.

Type HD 209458b into Google, and you'll find plenty of references to its apparent doom, including the nickname Osiris, the Egyptian god of the afterlife. One group came up with the term "chthonian planet" to describe what you get when a gas giant planet is whittled down to its rocky core — the assumption being that HD209458b is on its way to becoming just such a place.

Now Phil Arras and colleagues at the University of Virginia have another idea. They've been working on the question of what a magnetic field might do in such a circumstance. Given that our own Jupiter has a very strong magnetic field, it's not a stretch to imagine HD 209458b has one too. Arras reasons that a strong-enough field would be very effective at trapping any ions that surround the planet. Instead of escaping forever, they would be directed toward the planet's magnetic poles — quite possibly creating spectacular aurorae in the process. To top it off, because the planet is so close to its star, that big envelope of gas must be thoroughly ionized — and therefore thoroughly magnetized — by the heat.

The picture this leaves us with is a planet that travels around embedded in a cloud of hot, ionized fog. The ions fill up the planet's magnetosphere like smoke in a bottle, but they're not stripped away. There's no need to explain why the planet is evaporating, because it isn't. "If you heat up a planet's atmosphere, then its gas can begin to flow out to infinity," says Arras. "But when you add a magnetic field, the gas is trapped."

This is not the first or even the best evidence that exoplanets can be magnetized. For Evgenya Shkolnik, the magic number that brings back the thrill of discovery is HD 179949. In 2003 she and Gordon Walker of the University of British Columbia published evidence that this star has a bright spot that moves around its surface ever three days, keeping perfect time with a hot Jupiter-sized planet that's orbiting with the same period. Their conclusion is that as the planet barrels through the star's atmosphere, or corona, its magnetic field is continually triggering the release of energy within the star's much stronger magnetic field. This energy is transferred down to a region near the star's surface, forming a hot spot that follows the planet, like a mobile, never-ending solar flare.

This kind of magnetic communication between planet and star had been predicted by others but it was Shkolnik and Walker who first saw it in action. "It was tremendously exciting," Shkolnik recently told me when she recounted the story.

But the effort has not stopped at simply looking for evidence of planetary magnetic fields. "If a planet has a magnetic field then we can start inferring things about its internal structure," says Shkolnik, who is now based at the Carnegie Institution of Washington.

More than a half century ago, two of Shkolnik's predecessors at Carnegie, Bernard Burke and Kenneth Franklin, accidentally discovered the first known magnetic field around another planet. In 1955, using an early radio array made up of wire strewn across a farmer's field on the north shore of the Potomac River, the pair set about scanning the skies for signs of radio waves from distant stars and galaxies. What they got instead — to their surprise and everyone else's — were regular bursts of static from Jupiter, which happened to be high above the horizon at the time. These proved to be telltale emissions from electrons trapped in Jupiter's magnetic field.

A generation later, the magnetic personalities of other, more distant Jupiters are beginning to reveal themselves. The prospect of finding another Earth, complete with its own life-protecting magnetic field, could be just over the horizon.

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Ivan Semeniuk is host of The Universe in Mind podcast and a science journalist in residence at the Dunlap Institute for Astronomy and Astrophysics, University of Toronto.

At the end of the last ice age, North America was in the midst of an epic thaw. The giant glaciers that had covered nearly all of Canada and the northern United States for millennia were receding fast. Spring was in the air.

This was, presumably, good news for all the exotic creatures that populated North America at the time, including the mammoths, mastodons, giant sloths, sabre-tooth cats, dire wolves, and several other large species, collectively known as the Pleistocene megafauna. It was also good news for the Clovis people, a population of Paleolithic hunters who found their way into North America from Siberia, via an ice-free corridor that ran just east of the Rockies. They had plenty of big game to live on, as their kill sites demonstrate.

So what happened?

Just under 13,000 years ago, with everything looking rosy, the climate suddenly took a precipitous swing back toward the deep freeze. Temperature plummeted. At the same time, the big animals disappeared — and so did the Clovis people. Today what we consider to be the native wildlife of North America is just a pale shadow of what once was. A moose is impressive, to be sure, but there should also be mastodon running around in the forests of Appalachia, and curvy-tusked mammoth right alongside those buffalo on the Great Plains.

Theories abound to explain what exactly eliminated these giant species. It’s possible that a sudden release of meltwater into the North Atlantic temporarily shut down the ocean’s circulatory system. Without the Gulf Stream to bring warm water up from lower latitudes the climate would have cooled, forests would have dried out and burned, and large species would have been severely compromised. Add humans to the mix and perhaps excessive hunting was the straw that broke the prehistoric pachyderm’s back.

Or maybe a comet did it.

That’s what one team of researchers is now saying, and they base their conclusion on microscopic diamonds that have turned up all over the Northern Hemisphere in sediments that date back to the extinction of the megafauna. However, critics counter that this scenario is, at best, highly unlikely. Now everyone is looking for new clues to resolve the controversy.

You can read about the current state of this topic in the September issue of Sky & Telescope magazine. And in the latest episode of The Universe in Mind podcast you can hear from researchers on both sides of the debate. It’s a great story — one we certainly haven’t heard the last of yet.

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Ivan Semeniuk is host of the podcast The Universe in Mind and a science journalist in residence at the Dunlap Institute for Astronomy and Astrophysics, University of Toronto.

Astronomy is the ultimate “seeing” science. Unlike our experience of everyday reality, there’s no sound out in the cosmos, so the processes and events that we observe in the universe unfold before us like a silent movie.

Now some researchers are trying to add a soundtrack to that movie. They are the ones searching for gravitational waves — ripples in space-time caused by the rapid motion of massive objects. If detected, these waves will offer an entirely new way to perceive the universe — one that has more in common with hearing than seeing.

In Episode #11 of The Universe in Mind podcast, we hear from Neil Cornish (Montana State University, Bozeman) about recent progress in the hunt for gravitational waves, and we get a bold prediction for how soon these elusive but revealing signals will be detected.

Jacqueline Radigan of the University of Toronto also drops by to explain how brown dwarfs — objects that are midway between stars and planets — can have their own weather patterns

Enjoy the program!

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Ivan Semeniuk is host of the podcast The Universe in Mind and a science journalist in residence at the Dunlap Institute for Astronomy and Astrophysics, University of Toronto.

There are only so many mountains where you can put a telescope on this Earth and when you’re trying to build the biggest telescope ever you want to choose a good one. That much is obvious, but the selection of a site for a major observatory is no simple matter. Rather, it is the result of a complex interplay of astronomy, geography and economics. If you want to see where the pristine but unfeeling grandeur of the cosmos comes cheek to jowl with the messy subjectivity of human affairs then eavesdrop on a telescope site-selection meeting.

Last week, the Thirty Meter Telescope (TMT) consortium announced the result of a long deliberation over where to park their 1,430-ton spyglass, to be built over the next 10 years. This may not seem like a big surprise — after all, Mauna Kea is already home to the largest concentration of major telescopes in the world. But there is a strong contender in Chile named Cerro Armazones that could have come out ahead.

I’m interested in understanding why Hawaii prevailed. Sure enough, there’s a politics-behind-the-science story here. But there’s an even more fascinating science-behind-the-politics story too.

My guide in teasing out the finer points of the TMT decision is Rene Racine, a TMT board member and professor emeritus at the Université de Montréal. Racine has first hand experience with both Hawaiian and Chilean skies, having helped to build one observatory (Univeristy of Toronto Southern Observatory) on Las Campanas and directed another (Canada-France-Hawaii Telescope) on Mauna Kea.

To get an idea of why this decision matters so much let’s consider a few facts. First, TMT is one of a new generation of telescopes that is expected to vault ground-based astronomy to previously unimagined heights. As its name suggests, its primary mirror is 30 meters across. It’s composed of 492 hexagonal segments which collectively will have a light gathering area 144 times that of the Hubble Space Telescope and nearly 10 times the resolution at infrared wavelengths. That’s according to TMT’s own PR, but clearly there’s nothing like it around today.

TMT will also cost between 1 and 2 billion dollars when all is said and done. This is not quite at the scale of the world’s biggest science projects, like the Large Hadron Collider or the James Webb Space Telescope, but it’s getting there. In fact, TMT and other proposed observatories of this generation may end up being the biggest telescopes on Earth for all time because the funding required to go even larger would more logically be directed towards putting telescopes in orbit.

TMT has its roots at Caltech, which operates the mighty Keck telescopes on Mauna Kea. Given the infrastructure at hand on the Hawaiian peak it would seem inevitable that TMT would end up there. Furthermore, for reasons of politics and access, US partners in the project are naturally interested in seeing TMT built on US soil. Canada, another partner, is also well ensconced at Mauna Kea. Ditto for the Japanese, who are looking to buy into TMT. Japan already has its big Subaru telescope on Mauna Kea, so the Japanese like the idea of keeping their eggs in the Hawaiian basket.

But back in 2002, the Office of Hawaiian Affairs filed suit to prevent Keck from adding two small outrigger telescopes citing lack of an adequate environmental assessment. It was a shocking wake-up call for astronomers, who suddenly realized that not everyone with a stake in Mauna Kea was thrilled with the prospect of yet more construction on a site that is sacred to native Hawaiians.

For TMT that means being open to possibilities beyond Mauna Kea, and most of those possibilities are in Chile. Cerro Armazones is a particularly appealing choice. It is within sight of Paranal, which is home to Europe’s most advanced observatory (the VLT) and it may be slightly better for observing. The Chilean government rolled out the red carpet for TMT, giving it the first crack at Armazones.

On top of that, TMT has two competing megascopes that are also on the drawing board. One of those, the 27-meter Giant Magellan Telescope (GMT) has already settled on a location in Chile. The other, the European Extremely Large Telescope (EELT) is giving Chile strong consideration.

(Click here for S&T.com's list of the world's largest optical telescopes.)

That’s the politics. But here’s where the science comes in. From a big telescope’s perspective, the atmosphere has two layers. The lower atmosphere is basically the first few hundred meters or so. It’s the boundary layer where proximity to the surface affects the movement of air. The upper atmosphere is everything else.

Turbulence in the atmosphere is what limits how well optical telescopes can see the sky. It’s like looking at pebbles at the bottom of a stream. The more waves there are on the surface of the water the more distorted the image of the pebbles becomes.

If you’re talking about natural seeing conditions — literally, how sharp the stars appear — then Armazones is close if not better than Mauna Kea despite being a full kilometer lower in altitude. On top of that, Armazones is located in the Atacama Desert, the driest place on Earth. That means it has many more clear nights than Mauna Kea. Hour for hour, any telescope on Armazones is bound to be more productive.

But now let’s bring adaptive optics into the picture. This is the technology that allows a big telescope to monitor air movement and deform its own optics to compensate for atmospheric turbulence. It’s only effective at infrared wavelengths but what it does is amazing. Adaptive optics essentially gives the telescope a view that is similar to what the pebbles in the stream would look like if the water were perfectly still.

Adaptive optics is a big part of TMT’s design. It will work both on Mauna Kea and Armazones, but astronomers expect it will work better on Mauna Kea. This is because the upper atmosphere — the part above the boundary layer — is somewhat less turbulent above Mauna Kea than it is above Armazones. Why? According to Racine it’s partly a function of latitude. Because Mauna Kea is nearer the equator it’s relatively unaffected by the jet streams that flow at higher latitudes both north and south. Armazones’ upper atmosphere is a bit more turbulent in comparison and so somewhat harder for adaptive optics to deal with.

Racine estimates that more than half of TMT’s observing projects will be in the infrared. The likely targets at these wavelengths include the earliest galaxies, the birthplaces of stars and newborn exoplanets — all hot topics. The chance to maximize the impact of adaptive optics on these objects is a big factor in the TMT decision to go with Mauna Kea.

So what about the Office of Hawaiian Affairs? Racine says the dispute over the Keck outriggers is still cause for concern, but the TMT group has made Hawaiian community input a high priority. There’s still the possibility that there will be future problems but in this case the benefits outweigh the risk.

That makes Cerro Armazones the most eligible mountain without an observatory—a fact that will not have escaped the attention of the European Extremely Large Telescope. The Europeans have political factors of their own to deal with, including some strong incentives to locate on La Palma, one of the Spanish Canary Islands. They’ll make their site decision by the end of this year, which means we’ll soon have another chance to see the geopolitics of astronomy in action.

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Ivan Semeniuk is host of the podcast The Universe in Mind and a science journalist in residence at the Dunlap Institute for Astronomy and Astrophysics, University of Toronto.

Sometimes, seeing is not just believing, seeing is celebrating.

Astronomers working with the Herschel mission are in good spirits this week after capturing a stunning new image of M51, the Whirlpool galaxy. The galaxy’s elegant spiral arms can easily be discerned in the infrared image, which is far sharper at long wavelengths than images by Herschel's predecessor, NASA’s Spitzer Space Telescope.

“It’s very exciting to see the first images from Herschel,” says Christine Wilson of McMaster University in Hamilton, Ontario. Wilson leads the Herschel Key Project, which will characterize interstellar dust in nearby galaxies.

“M51 is one of our targets,” says Wilson. “The picture is really spectacular and I have been thinking today about what it means.”

The sharpness of the image comes as a relief to project scientists, since Herschel's optical components cannot be adjusted after launch. Because of the way the spacecraft was designed and constructed it was not possible to test all the telescope's optical components together at the same time.

Among the interesting details in the new image is the slight color difference between M51 and a smaller elliptical galaxy, which appears as a bright bluish dot in the upper left part of the image. This galaxy is passing by the Whirlpool and has been gravitationally interacting with it for millions of years. According to Wilson, the contrasting colors hint at “some difference in the emission processes in the two galaxies.”

The Herschel Key Project will focus on 13 relatively close galaxies including some that are merging or have been disrupted by past collisions. Among the questions the project seeks to answer is whether different kinds of galaxies, such ellipticals and spirals have different kinds of dust mixed in among their stars.

Herschel is ideal for measuring the size, composition and temperature of dust grains within the Milky Way and in distant galaxies. Dust naturally absorbs light from stars and re-emits that energy at infrared wavelengths. The study of dust is particularly important in astronomy because dust is crucial to the formation of solar systems with rocky planets like Earth.

With a primary mirror 3.5 meters across, Herschel became the largest space telescope ever when it was launched by the European Space Agency on May 14th. It is currently on its way to L₂, a point some 1.5 million km away where the combined gravitational pull of the Sun and Earth allow spacecraft to travel in sync with our planet.

Herschel’s relatively larger mirror accounts for why its view is so much sharper at some wavelengths than Spitzer’s. You can find a comparison of the two here.

M51 is located about 25 million light-years from the Milky Way. Its grand design spiral shape and face-on orientation have made it a perennial favorite with backyard astronomers.

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Ivan Semeniuk is host of the podcast The Universe in Mind and a science journalist in residence at the Dunlap Institute for Astronomy and Astrophysics, University of Toronto.

As molecules go, formic acid isn’t much to look at. You’ve got a carbon atom, two oxygens and two hydrogens. Stick them together to make a little tinker toy arrangement and there it is.

Nevertheless, formic acid has a way of commanding one’s attention. You’ll know this if an ant has ever bitten you, since formic acid is the active ingredient in ant venom. (It’s in bee venom too, but bee stings are more complicated.)

It also commands the attention of scientists interested in the origins of life. This is because formic acid is merely the simplest and shortest version of a fatty acid. In true tinkertoy fashion you can replace one of it hydrogen atoms with a chain of carbons and end up with all manner of compounds that are biologically important--if nutritionally suspect. Or you can also attach an amino group to formic acid and make an amino acid instead.

All this plays into the question of how life on Earth came to be. Astronomers can detect formic acid in the cold dark recesses of interstellar space. Did the formic acid up there somehow play a role in the emergence of the first biologically active molecules down here?

Now we may have part of the answer thanks to the Tagish Lake meteorite. It’s been nearly ten years since this blazing fireball ripped across the early morning skies of Yukon and northern British Columbia. What witnesses thought was an incoming missile proved to have a happier explanation. It was a massive meteorite—over 50 tonnes—that disintegrated as it plowed through Earth’s atmosphere at high speed.

In what is surely the biggest break in meteorite history, a fragment of the meteorite was picked up and retrieved by a passer by who used a plastic baggie to handle it and promptly tossed it in his freezer. Sitting there among the steaks, the meteorite remained uncontaminated by human hands and its temperature never rose above freezing.

This turned out to be very important, since the Tagish Lake meteorite has the highest carbon content of any meteorite ever recovered. It offers a fascinating profile of what kind of material might have made its way to Earth’s surface billions of years ago.
A decade after its recovery, techniques are still being developed to tease interesting details out of the Tagish lake meteorite. The latest is the report of abundant quantities of formic acid, four times higher than seen in any other meteorite.
The work was done by Dr. Chris Herd and colleagues at the University of Alberta in Edmonton. To find out more I spoke with Chris Herd. You can find the full interview in the latest episode of the Universe in Mind podcast.

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Ivan Semeniuk is host of the podcast The Universe in Mind and a science journalist in residence at the Dunlap Institute for Astronomy and Astrophysics, University of Toronto.

One of the true pleasures in science comes when a new and surprising fact is uncovered about something thought to be utterly familiar. Such is the case this week with the revelation that Spica, one of the best-known stars in the night sky, is an eclipsing binary. Every 4.0145 days one of the two separate stars that makes up this system crosses in front of the other, blocking a portion of its light.

How could astronomers have missed this fact? It’s no scandal. Spica’s eclipses are the merest grazes. Each time it happens the total light output of the system dips by less than one hundredth of a visual magnitude. Nevertheless, these events are of interest to science because they offer a greatly improved understanding of the two star's sizes and shapes and the complex physics at work in a nearby and rather special star system. Astronomers have known since 1890 that Spica was a spectroscopic binary, but now we have a better handle on it.

What's most amazing is that the eclipses were seen at all. For that we have MOST to thank — the hardest working microsatellite in astronomy.

MOST stands for Microvariability and Oscillation of Stars. It’s a suitcase-sized satellite that specializes in staring at stars for weeks on end — something that is not practical with ground-based telescopes that have to deal with day and night. And because it's above our twinkle-inducing atmosphere, MOST can measure star brightnesses with much higher precision that is ever possible from the ground.

Maarten Desmet, a Ph.D. student at the Institute for Astronomy, Katholieke Universiteit in Leuven, Belgium, and his supervisor Conny Aerts, led the Spica campaign in collaboration with the MOST team. The observations involved more than three weeks of steady staring at Spica to get a crisp, complete, light curve of several complete orbits.

What makes detecting the eclipses a challenge is that Spica already varies in brightness once per orbit. Spica's two components are both intensely hot and pale blue. The larger and brighter of the pair is a slightly pulsating variable of the Beta Cephei variety. Moreover, they orbit one another so closely that their shapes are distorted by their mutual gravity into egg shapes, (prolate spheroids), with their long axes directed toward one another.

Historically, this configuration led to confusion about whether Spica is an eclipsing binary. Because prolate spheroids look bigger when viewed sideways (click here to manipulate a prolate spheroid and see for yourself!), Spica gets marginally brighter when its two stars are oriented side-on to us rather than end-on.

This so-called “ellipsoidal” variation was originally mistaken for a slight periodic eclipse. You can find it misidentified this way in the venerable Burnham’s Celestial Handbook. By the 1970’s, however, that view was changing, and in more recent literature Spica is referred to as non-eclipsing.

The books will have to be corrected once more now that Spica’s grazing-eclipsing nature has been established by MOST. The variations are much smaller than those previously attributed to eclipses, so this effect is not what was measured in earlier decades.

A Pre-Supernova to Study

So what do astronomers get out of this? Plenty, says Jason Aufdenberg of Embry-Riddle Aeronautical University in Florida, who was not a member of the discovery team. For starters, we get the diameter of the eclipsed star, putting an upper limit on its mass. We also get a more accurate value for the inclination of the system’s orbit (how it’s oriented with respect to our line of sight). These can help nail down the more complex aspects of the system, including how the mass distribution in the two stars is affected by their tidal interactions.

“This a fascinating system,” says Aufdenberg.

At 260 light years away, Spica offers one of the nearest examples of stars that are likely go supernova one day. The better they can be characterized the more confident astronomers can be about using them as a reference to understand more distant stars of the same type.

“The eclipses mean it’s one-shop-stopping for this type of star,” says Jaymie Matthews of the University of British Columbia, who is lead scientist for MOST.

The results will be unveiled tomorrow at the Stellar Pulsationmeeting in Santa Fe, New Mexico.

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Ivan Semeniuk is host of the podcast The Universe in Mind and a science journalist in residence at the Dunlap Institute for Astronomy and Astrophysics, University of Toronto.

There are good days and there are bad days, but by any measure the period around 3.9 billion years ago was the worst time to be living on Earth–or for that matter anywhere else in the solar system.

This is the period known as the Late Heavy Bombardment (LHB), when giant chunks of debris were let loose to batter the inner planets. No obvious traces of this terrifying episode remain on Earth, but we know it occurred thanks to the Moon. The circular features that give the man-in-the-moon its hollow-eyed expression are the marks of giant impacts that all date to around this time. Earth, with its larger surface area and stronger gravity, would have attracted even more big blows.

How bad was it? Estimates suggest about 50 objects at least 100 kilometers across pummeled the Earth during the LHB. (For comparison, it was a single 10 kilometer-diameter asteroid that is believed to have taken out the dinosaurs.) These are ocean-vaporizing events that would have liquefied large swaths of the planet’s surface.
Yet, despite all this, Oleg Abramov and Stephen Mojzsis say that life survived.

The two University of Colorado, Boulder researchers created a simulation of the Late Heavy Bombardment to study its effects on the temperature of the Earth’s crust down to a depth of four kilometers. (Today bacteria have been detected at comparable depths.) Not surprisingly they found that regions directly hit by an impact would have been sterilized of micro-organisms, the only possible life around at that time. But—surprisingly—a few thousand kilometers away, Earth’s crust would still be stable and capable of supporting ancient bacteria.

Some of those bacteria may even have thrived during the bad years. The giant impacts would have fractured Earth’s crust, creating passageways for hot magma and hydrothermal vents. This is the sort of environment that heat loving organisms known as thermophiles like best.

And it appears they would not have been alone. The study shows that even mesophiles, which require temperatures between 20° and 50° Celsius, could have found ample refuge to ride out the worst of the bombardment and survived to recolonize the planet.

There are at least two interesting implications to this. The first is that life on Earth may be older than we think. Because the Late Heavy Bombardment was so extreme, it’s been previously speculated that it wiped the planet clean of life. Now Abramov and Mojzsis say that’s not what happened.

The earliest (isotopic) evidence for life on Earth dates back to 3.83 billion years ago. That’s getting uncomfortably close to the Late Heavy Bombardment and it doesn’t give life much time to get started from scratch. But if life was already present well before the Late Heavy Bombardment, there’s less of a mystery about how it got going so fast.
The second implication is for life elsewhere in the solar system and beyond. If life on Earth could survive the Late Heavy Bombardment then presumably life on Mars could too. So could life on other planets in other solar systems where the same bombardment scenario may have occurred.

Life is funny that way. Getting it going must require just the right conditions and plenty of time—otherwise someone would have seen it spontaneously come to be in a lab somewhere. Yet, once life is established, it seems like you just can’t keep it down.
For my money, British rapper Michael Skinner (aka The Streets) says it best in his song “On the Edge of a Cliff”:

For billions of years since the outset of time
Every single one of your ancestors has survived

Every single person on your mum and dad's side

Successfully looked after and passed on to you life.
What are the chances of that, like?
It comes to me once in a while

And everywhere I tell folk it gets the best smile.

The results of the new study were published last week in Nature. For more on this and other revelations about the origins of life, there’s an interview with Oleg Abramov in the next episode of The Universe in Mind podcast.


Ivan Semeniuk is host of The Universe in Mind podcast and a science journalist in residence at the Dunlap Institute for Astronomy and Astrophysics, University of Toronto.

What do exploding stars and presidential politics have in common? The two come together in the person of Donald Lamb, a University of Chicago astrophysicist and director of the Flash Center , where researchers study thermonuclear detonations in space.

Lamb also lives in Hyde Park, the Chicago neighborhood that has become world famous thanks to another long time resident, Barack Obama. Lamb became an early supporter of the current president going back to Obama’s state senator days. He joined the presidential campaign in 2007 and soon became identified as one of the prominent scientists who helped sell Obama to the reserach community. After the election he was part of the transition team that helped shape the new administration’s science and technology agenda.

In the latest episode of The Universe in Mind podcast, Lamb speaks in detail about his experiences on the campaign trail and about Obama’s attitudes toward science. He also speaks about his own area of expertise: Type Ia supernovae, and shares some recent insights into how these cosmic H-bombs work.

Type Ia supernovae have become increasingly important because they are the brilliant standard candles that allow astronomers to measure the distances to galaxies halfway across the universe. A decade ago such measurements led to the discovery of dark energy, the enigmatic phenomenon that is causing the expansion of the universe to accelerate.

Lamb and his colleagues are concerned with exactly how these explosions unfold. It’s a science of extremes, involving events of unimaginably high energy playing out over fractions of a second.

One of the most surprising discoveries to come out of this work is that type Ia supernovae can be thought of as exploding from the outside in. This kind of supernova always occurs in a close binary system, where gas from one star can spill over onto a white dwarf companion. A white dwarf is already about one million times the density of the Sun. The additional material further increases the pressure and temperature in the white dwarf’s interior until spontaneous bubbles of nuclear burning begin to form.

Lamb was part of a team that did the first full 3-D model of a white dwarf exploding under theses circumstances. What they found was that the tiny flame that starts somewhere inside the white dwarf rises very quickly, like a hot air balloon. In an instant it is already at the surface of the star. There, gravity confines it like an invisible lid, so the burning front then races across the surface of the white dwarf and meets itself on the far side. The shock that results is what turns the burning into an all-consuming detonation. You can watch a video that shows this scenario in action, and it’s quite a spectacle.

It’s a big change from how these dramatic explosions were once envisioned. And according to Donald Lamb, it’s change we can believe in.

Ivan Semeniuk is host of The Universe in Mind podcast and a science journalist in residence at the Dunlap Institute for Astronomy and Astrophysics, University of Toronto.

Here’s one way of summing up the scientific revolution in two words: data matters.

Surely Galileo deserves credit for imagination and intellectual bravery. But what really sets him apart from the generations of thinkers that preceded him is the telescope. With Galileo, for the first time, there is genuinely new data available. The telescope is not just an aid to the eye, but to the brain. When it’s applied to the heavens, an observer—any observer—can see things that Aristotle never dreamed of, and so come away “smarter” and better informed about the nature of the cosmos that the greatest minds of antiquity. With the scientific revolution comes the realization that thinking deeply doesn't get us very far unless we can also improve the quality and the reach of our data. Seeing better makes us smarter.

With that thought in mind, this was a banner week for beefing up our cosmic IQ.

The successful launch of the Herschel and Planck spacecraft, along with the ongoing renewal of the Hubble Space Telescope, means that astronomers are about to take another big leap forward in the data department, with the expectation of a more nuanced take on the universe to follow, and quite possibly some radical shifts in our thinking.

Herschel is the much-anticipated infrared satellite that will pick up where NASA’s Spitzer Observatory left off. It’s 3.5-meter mirror is the largest ever launched (at least for astronomical purposes – there could be bigger spy satellites up there somewhere). It will probe longer infrared wavelengths than Spitzer, pushing infrared astronomy towards cooler targets within our own galaxy and more ancient epochs in the distant universe.

Planck is the next generation effort to explore the cosmic microwave background—the relic radiation that was released just a few hundred thousand years after the Big Bang, when the universe first cooled enough to form hydrogen gas. Its predecessor, the WMAP satellite, helped transformed our picture of the early universe—a picture that now includes dark matter and dark energy in addition to ordinary matter. Planck will certainly refine this view but it will also take us closer to the underlying question of what produced the Big Bang in the first place.

Along with the Fermi Gamma-Ray Observatory, launched last year, they represent the first truly 21st century space observatories. They are the next step after the Hubble generation of great observatories, which were conceived during the 1970’s and 80’s and launched mainly in the 1990’s.

Meanwhile, the Hubble itself is in the process of being turned into something pretty close to a 21-century observatory also. Nearly 20 years after it’s launch, Hubble in the midst of a complete overhaul that will see (we hope), two key instruments repaired and two new instruments added. The new hardware includes the Cosmic Origins Spectrograph. Like Herschel and Planck, this instrument is a sophisticated effort to address one of the most basic questions of existence: where do we come from?

It’s hard to imagine what Galileo would have made of the technology, but he would have understood the motivation behind these spacecraft: They are built to smarten us up.

Ivan Semeniuk is host of The Universe in Mind podcast and a science journalist in residence at the Dunlap Institute for Astronomy and Astrophysics, University of Toronto.

Once upon a time a little satellite gazed at a nearby star and seemed to see a solar system in the act of being born. There was no picture of the blessed event, just an unusually large amount of infrared energy coming from the star. This is exactly what you would expect if the star were surrounded by dust, which absorbs starlight and re-emits it as heat. And dust is what you would expect to find where planets are forming.

The satellite was IRAS (Infrared Astronomy Satellite) and the star was Fomalhaut, a well-known neighbor to our Sun located just 25 light years away. I still remember the excitement that surrounded the discovery; it was one of the first direct hints that our solar system is not unique.

How times have changed! Astronomers don’t have to speculate about the dust around Fomalhaut anymore. Thanks to the Hubble Space Telescope they can see it directly, in the shape of an elegant ring circling around the star. They don’t have to speculate about planets either. The Hubble has spotted one of those too, orbiting Fomalhaut just inside the ring.

Now it appears we have something new to consider: Could we be witnessing a system of moons forming there too?

It’s a fitting question for the International Year of Astronomy, which marks the 400th anniversary of Galileo first use of the telescope and his discovery of Jupiter’s four big moons. These moons probably formed by condensing out of a disk of matter that was circling around the infant Jupiter—just as Jupiter formed from a disk of matter surrounding the infant Sun.

The idea of disks within disks brings to mind a quip by Jonathan Swift, best known in its rephrasing by Augustus De Morgan : “Great fleas have little fleas upon their backs to bite ‘em, and little fleas have lesser fleas, and so ad infinitum.”

The idea applies to Fomalhaut because of the peculiar properties of Fomalhaut b, the planet detected there. Even for the Hubble, the planet appears as nothing more than a dot, first imaged in 2004. (The confirmation came when a second observation taken in 2006 later showed that it had moved some distance along its orbital path. This ruled out the possibility that the object was just a background star.)

The dot that Hubble sees is mainly infrared light, assumed to be from a Jupiter-type planet that is radiating the heat of its own formation. A dot is not a lot to go on, but at least its brightness can tell you about the planet’s size: a bigger planet would correspond to a brighter dot. At the same time, the gap between the planet and the inner edge of the ring can give you a limit on the planet’s mass, since a heavier planet at the same location would have a more disruptive effect on the dust particles in the ring.

Oddly, in the case of Fomalhaut, these two pieces of information do not seem to agree. The planet’s position with respect to the ring suggests an object that is only about half the mass of Jupiter, yet the dot is much brighter than you would expect from such a pint-sized gas giant. An appealing possibility is that a disk of debris around the planet is responsible for its elevated brightness. In fact, measurements through different filters suggest the dot is giving off reflected starlight as well as emitted planet light. A disk would do this.

A disk around the planet could mean that moons are forming there. However, the planet’s reflected light grew dimmer between the two years it was observed. Could the disk be disappearing that fast? Or is it the product not of moon formation but of something more radical and temporary, like dusty debris from a giant comet collision with an existing moon, for example.

James Graham is an astronomer at the University of California, Berekeley, and part of the team that discovered Fomalhaut b. The only way to know what’s really going on, he say, it to take more images, which can’t happen until the Hubble is repaired. This was supposed to be last year but is now scheduled to happen next month. For Graham and his colleagues every day matters. If the planet is changing that fast, then potentially important information is now being lost. “That’s why it will be important to get another image as soon as possible after Hubble’s back,” says Graham.

When it comes to fleas, it's hard to wait.

Ivan Semeniuk is host of The Universe in Mind podcast and a science journalist in residence at the Dunlap Institute for Astronomy and Astrophysics, University of Toronto.

Imagine a steep mountainside burdened with snow, its powdery mass poised over a quiet Alpine valley. You don’t have to be a backwoods skier to recognize the inherent danger in this situation. Under the right conditions, the stable and stationary snowpack can suddenly fracture and dissolve into a rushing avalanche that sweeps away everything in its path. Yet, until that happens, the scene is one of utter calm and serenity.

Now imagine it’s a warm summer night and you’re somewhere far from city lights, enjoying a spectacular view of the stars. The Milky Way glows like a ribbon of light weaving its way through the constellations. It’s also a moment of calm and serenity—or so seems. But now a new look at our home galaxy suggests the Milky Way may have more in common with avalanches than anyone realized.

This insight comes from the BLAST mission, short for “Balloon-borne Large-Aperture Sub-millimeter Telescope.” As the names suggests this impressive detector, nearly as large in aperture as the Hubble Space Telescope, was made to do its work while suspended from a helium filled balloon, some 35-kilometres above sea-level. There’s not much air left at that altitude, and certainly not much water vapor. Such conditions are ideal for looking at the universe in the “submillimeter” part of the spectrum—a kind of astronomical grey zone that falls between infrared and radio waves. This window turns out to be crucial to astronomers interested in the formation of stars, whether in the Milky Way or in distant galaxies half a universe away.

Back in December 2006, BLAST rode the steady winds of the Antarctic summer and observed the submillimetre universe for 11 continuous days. Earlier this month astronomers published their findings from the BLAST flight, garnering cover-page status in the journal Nature. One of the more curious results from the mission is that everywhere BLAST looked at gas within the Milky Way, it found “cold cores”—dense concentrations of gas that should have collapsed and turned into stars by now, but so far have managed to avoid doing so.

What’s stopping them is anybody’s guess. One theory is that magnetic fields are propping up the cold cores, so that gravity can’t take over and initiate the star-forming process. Whatever the explanation, you have to wonder what our galaxy would look like if all those dormant cores were to suddenly collapse and make news stars. It may well resemble a “starburst” galaxy, a galaxy virtually exploding with star formation. We see starburst galaxies in different places. One of the nearest is M82, a smaller galaxy near the large, graceful spiral M81. It’s long been supposed that gravitational interaction with M81 is what triggered M82 to become a starburst, but it’s never been too clear exactly how that happens. All those cold cores may provide an answer. It cloud be that many normal galaxies could be converted into starbursts, if their cold cores are tickled in the right way.

Such a stellar avalanche way well be in our future: As our Milky Way draws ever nearer to the Andromeda galaxy it’s clear that in a few billion years (or less) the two will collide. When that happens all the cold cores seen by BLAST may not stay cold. The impending collision could set off a round of celestial formation not seen in these parts since the Milky Way was born. Presumably new planets and the possibility of new life and new civilizations will also be part of the starburst equation. Humans may not be around to see it, but the future Milky Way-Andromeda merger could be the beginning of a golden age for life. And when you’re considering an impending avalanche, it’s important to look on the bright side.

Ivan Semeniuk is host of The Universe in Mind podcast and a science journalist in residence at the Dunlap Institute for Astronomy and Astrophysics, University of Toronto.