Gravitational Lensing: This image of galaxy cluster MACS J1206.2-0847 shows the gravitational lensing effect of dark matter on distant galaxies. In a new exoplanet population paper, astronomers used microlensing to sense the presence of planets around other stars. The lensing was not as extreme as this, but works somewhat like a magnifying glass, brightening the light of a star lined up behind the planetary system.

“Planets are like bunnies; you don’t just get one, you get a bunch,” said Seth Shostak, a senior astronomer at the SETI Institute who was not involved in this research. “So really, the number of planets in the Milky Way is probably like five or 10 times the number of stars. That’s something like a trillion planets.”

Of course there’s no way to know, at least not yet, how many of these worlds could be hospitable to forms of life as we know it. But the odds alone are tantalizing, Shostak said.

“It’s not unreasonable at this point to say there are literally billions of habitable worlds in our galaxy, probably as a lower limit,” he said. “Maybe they’re all sterile as an autoclave, but it doesn’t seem very likely, does it? That would make us very odd.”

“The numbers are huge by any human standard, but we are still looking at only a tiny bit of our galaxy,” said John Gribbin, an astronomer and science writer who just published a book called “Alone in the Universe.” “[This research] does further our understanding of how things like planets form and how stars form, but there is a long way to go before we can say there is life on any of these planets, and further to go before we get to civilization.”

The new planetary plenitude is derived from a six-year survey of millions of stars studied with an international network of southern hemisphere telescopes. Astronomers used a delicate detection method called gravitational microlensing, which is one of three trusty ways to find extrasolar planets. Kepler uses the transit method, detecting blips in star brightness as planets cross in front of them. Other observatories use the radial velocity method, measuring the wobble caused by the gravitational tug of a planet on its star. Both of these are helpful for finding planets that are either huge or hug tightly to their stars. But the gravitational microlensing method can be used to find planets over a wider mass range and a wider orbital distance.

La Silla Observatory: The Milky Way seen above the dome of the Danish 1.54-metre telescope at ESO’s La Silla Observatory in Chile, used to search for exoplanets using the microlensing technique. The central part of the Milky Way is visible behind the dome of the ESO 3.6-metre telescope; on the right, the Magellanic Clouds.

It works by using the host star and its putative planets as a lens. The gravitational field of the host solar system magnifies the light of a star in the background. If the host star does have a planet, the planet essentially widens the lens, and this is an effect that can be measured. Such an alignment is incredibly rare, so an international team of researchers examined 100 million stars every night and noted ones with promising light curve amplifications, examining them in higher resolution. From 2002 to 2007, the team observed 500 such stars. In 10 cases, they could directly see the lensing effect of a planet. A statistical analysis showed one in six of the stars studied hosts a planet of similar mass to Jupiter, half have Neptune-mass planets and two thirds have super-Earths. Combining the results suggests that the average number of planets around a star is greater than one, the astronomers say in a new Nature paper.

“Together, the three methods are, for the first time, able to say something about how common our own solar system is, as well as how many stars appear to have Earth-size planets in the orbital area where liquid what could in principle exist as lakes, rivers and oceans — that is to say, where life as we know it from Earth could exist,” said Uffe Gråe Jørgensen, head of the Astrophysics and Planetary Science group at the Niels Bohr Institute at the University of Copenhagen and an author of the paper.

With so many planets, it could be easy to assume the odds have just gotten much better for alien life hunters, but it’s not necessarily the case because scientists still don’t know what’s necessary for life to form, said Paul Davies, a cosmologist and astrobiologist at Arizona State University.

“How much real estate is out there doesn’t matter,” he said. “My guess is there would be some hundreds of millions of Earth-like planets in the Milky Way, but that is no good to you if the probability of life forming on one of them is one in a trillion.”

The lack of knowledge hasn’t stopped scientists from making educated guesses, however — take the Drake equation, devised by astronomer Frank Drake in 1961, which seeks to estimate the number of intelligent civilizations based on an equation of assumptions.

“All of the work that has been done since 1961 when this equation was concocted has gone in the same direction, namely, that our situation here is not so weird, not so strange, not so bizarre, not so special,” Shostak said. “We’re not unique, at least astronomically.”

We’re just one in millions.

A Plethora of Planets: This artist’s impression shows how common planets are around the stars in the Milky Way. The planets, their orbits and their host stars are all vastly magnified compared to their real separations. A six-year search that surveyed millions of stars using a technique called microlensing concluded that every star has at least one planet orbiting around it.

Behemoth Black Hole: This figure shows the immense size of the black hole discovered in the galaxy NGC 3842. The black hole is at its center and is surrounded by stars (shown as an artist’s concept in the central figure). The black hole is seven times larger than Pluto’s orbit. Our solar system (inset) would be dwarfed by it.

One of the monstrous black holes, in the center of the galaxy NGC 3842, weighs as much as 9.7 billion suns. It is about 331 million light-years away in the constellation Leo. The other one, NGC 4889, is of comparable or even greater mass, the researchers say — they’re not positive, but the numbers suggest it could be up to 21 billion solar masses. It’s 336 million light-years away in the Coma galaxy cluster.

The former heavyweight champ is a dwarf by comparison, tipping the scales at 6.3 billion solar masses. That black hole is at the center of the giant elliptical galaxy Messier 87.

Supermassive black holes of 10-billion-sun magnitude have been predicted based on the brightness of quasars, ultra-luminous distant objects that are largely thought to be spiraling discs surrounding the event horizons of black holes in the very early universe. But this is the first time such enormous black holes have ever been seen. They could be a missing link to the quasars, according to astronomer Michele Capellari, writing in a companion piece to the new black hole paper.

"These objects probably represent the missing dormant relics of the giant black holes that powered the brightest quasars in the early universe," she wrote.

To weigh the black holes, Nicholas McConnell and Chung-Pei Ma at the University of California-Berkeley used the Keck and Gemini observatories to measure the speed of stars moving around the black holes. The faster the stars were moving, the more gravity was needed to keep them in check, so the researchers used these velocities to calculate the black holes’ masses.

They found the black holes were much bigger than predictive math would suggest, which means astronomers still have a lot to learn about how the biggest black holes form and evolve.

“Our measurements suggest that different evolutionary processes influence the growth of the largest galaxies and their black holes,” the researchers write.

Our Own Black Hole, Through Adaptive Optics: Image of the center of our galaxy from laser-guide-star adaptive optics on the Keck Telescope. If a 10 billion solar mass black hole resided at the Milky Way’s center, its immense event horizon would be visible, as illustrated by the central black disk. The actual black hole at the galactic center is 2,500 times smaller, however.

Known as Gloria (GLObal Robotic telescopes Intelligent Array for e-Science), the three-year European project will ultimately include 17 telescopes on four continents, run by 13 partner groups from Russia, Chile, Ireland, the United Kingdom, Italy, the Czech Republic, Poland and Spain. Not only will users be able to control the telescopes from their computers, but they will also have access to the astronomical databases of Gloria and other organizations.

The telescope at Spain’s Montegancedo Observatory is serving as the model for Gloria. Located at the Universidad Politécnica de Madrid’s Facultad de Informática, it can already be remotely operated through the internet, using the university’s Ciclope Astro software. This same software will be used by all the Gloria telescopes, to ensure uniformity across the system.

The amount of time that individual users get on the telescopes will be based on their "Karma," determined by how popular their work is with their fellow users. It will reportedly be somewhat like YouTube, where users vote on each other’s video posts.

While the EUR2.5 million (US$3.4 million) project is intended to help armchair astronomers of all types explore the Universe for themselves, it will also be used for crowd-sourced research. The University of Oxford in particular will be using Gloria for its Galaxy Zoo project, in which users are recruited to help classify approximately a million galaxies. Astronomical events will also be broadcast on the system, to help promote Gloria and built its user community.

Yes, the universe itself will eventually outpace the speed of light. Just how this will happen is a bit complicated, so let’s begin at the very beginning: the big bang.

Around 14 billion years ago, all matter in the universe was thrown in every direction. That first explosion is still pushing galaxies outward. Scientists know this because of the Doppler effect, among other reasons. The wavelengths of light from other galaxies shift as they move away from us, just as the pitch of an ambulance siren changes as it moves past.

Take Hydra, a cluster of galaxies about three billion light years away. Astronomers have measured the distance from the Earth to Hydra by looking at the light coming from the cluster. Through a prism, Hydra’s hydrogen looks like four strips of red, blue-green, blue-violet and violet. But during the time it takes Hydra’s light to reach us, the bands of color have shifted down toward the red end—the low-energy end—of the spectrum. On their journey across the universe, the wavelengths of light have stretched. The farther the light travels, the more stretched it gets. The farther the bands shift toward the red end, the farther the light has traveled. The size of the shift is called the redshift, and it helps scientists figure out the movement of stars in space. Hydra isn’t the only distant cluster of galaxies that displays a redshift, though. Everything is shifting, because the universe is expanding. It’s just easier to see Hydra’s redshift because the farther a galaxy is from our own, the faster it is moving away.

There is no limit to how fast the universe can expand, says physicist Charles Bennett of Johns Hopkins University. Einstein’s theory that nothing can travel faster than the speed of light in a vacuum still holds true, because space itself is stretching, and space is nothing. Galaxies aren’t moving through space and away from each other but with space—like raisins in a rising loaf of bread. Some galaxies are already so far away from us, and moving away so quickly, that their light will never reach Earth. “It’s like running a 5K race, but the track expands while you’re running,” Bennett says. “If it expands faster than you can run, you’ll never get where you’re going."

And by “among,” we mean really one of just two (or three, depending on how you feel about Gliese 581g). Of the hundreds of exoplanets astronomers have recently discovered orbiting distant stars, only one–Gliese 581d–has been of the proper mass and distance from its star to be considered a strong candidate for habitability. Nearby Gliese 581g was once thought to be even more Earth-like than 581d, until some scientists asserted that 581g doesn’t even exist–a point that is still under debate.

HD85512b was discovered by the ESO’s High Accuracy Radial velocity Planet Searcher, or HARPS, in Chile (it’s the same instrument that found Gliese 581d. The data show that HD85512b is roughly three-and-a-half times the mass of Earth and rings its planet on the inner fringe of the so-called “goldilocks zone” that is not to distant and not too close to harbor liquid water. It’s size is also indicative of an Earth-like atmosphere of oxygen and nitrogen rather than the hydrogen and helium that dominate the atmospheres of larger worlds.

That alone makes it a potential candidate for life, but HD85512b has a couple of other characteristics working for it. For one, its orbit is almost perfectly circular and stable, so any climate on the planet wouldn’t swing wildly as it orbits. The planetary system is older than our own–a full one billion years older–so clearly it’s had enough time for life to potentially have developed there. in the same vein, its star is also more mature than our sun so it is less prone to violent solar activity that could destabilize the planet’s atmosphere.

Of course, there’s no way to tell if it actually has an atmosphere with modern instruments, and atmosphere is a critical ingredient here. Since HD85512b is orbiting on the inner portion of the goldilocks zone, it is more akin to Venus than to Earth in the amount of solar energy it’s taking on. But scientists speculate that cloud cover of fifty percent or more could offset that proximity enough to allow life to thrive–albeit a kind of life more suited to a balmy, hot environment (relative to Earth’s).

On average, Earth boasts 60 percent cloud cover so the idea of HD85512b having 50 percent isn’t so far-fetched. In fact, it’s probably more likely than the idea of humans building a light-speed spacecraft and then making the 31-year journey to go in for a closer look at the weather. But it’s fun to think about.

This is big news, of course, because if the ingredients for life were brought here from some external source, there’s always the possibility that the same thing has happened elsewhere in the universe–possibly many times over.

Scientists have been extracting fragments of DNA from meteorites for decades now, but there was never really hard proof that those pieces of biological molecules were native to the extraterrestrial object rather than terrestrial contamination that occurred when the object slammed into Earth. So while the idea of DNA riding aboard extraterrestrial objects has been floated before, this is the first time we’ve been presented real evidence backing that notion.

The idea isn’t that these building blocks are just passengers aboard meteorites, but that the chemistry inside asteroids and comets can actually manufacture the essential building blocks of biology. And a liquid chromatography and mass spectrometry analysis of sample meteorites and the environments where they were found seems to confirm this.

Here’s the basic gist of the findings: The LC and MS analysis separated and analyzed the component parts of the samples and found adenine and guanine, two of the components of the double helix that make up the code that tells our cells what to do. They also found hypoxanthine and xanthine, which don’t factor in to DNA but are used in other biological functions.

But more interestingly, the researchers found three nucleobase-related molecules: purine, 2,6-diaminopurine, and 6,8-diaminopurine. These last two are rarely used in biology, but they are like analogs for nucleobases–the same core molecule but structurally slightly different. That’s really important because if the meteorites were terrestrially contaminated, they wouldn’t be there (because they are not used in biology). But if the chemical processes going on inside an extraterrestrial object really are churning out prebiotic stuff, then you would expect to see all kinds of nucleobases–the ones used for biology, and others that aren’t.

Moreover, analysis of the Antarctic ice and Australian soil around where the meteorites were found showed the amounts of the two nucleobases as well as the hypoxanthine and xanthine to be drastically lower. If the contamination were terrestrial, one could expect equal amounts of the molecules (or less) to be present in the meteorite samples, certainly not more.

It’s a pretty convincing case, though one that will undergo a lot more scientific scrutiny. If comets and asteroids really are churning out the ingredients for life, it certainly changes our picture of life in the universe, and the possibility that other rocks out there might be harboring their own biological systems.

There are huge implications in that of course, provided the hypothesis turns out to be true. It underscores the idea that Mars could indeed be capable of harboring some kind of life. And it whets (wets?) the appetite for future Mars exploration, both robotic and–eventually–manned.

The evidence comes to us in the form of the finger-like features you see running down the slope of the crater in the pic above (and in the animation below). Regular observation shows that they appear during the warm months, extend themselves down sloping terrain, then fade away when temperatures drop in the fall. During the next Martian spring they return again. And while there are a few hypotheses floating around out there as to what might cause these features to appear, retreat, and appear again as the seasons change, the general consensus seems to be that briny water is the culprit.

Don’t get the wrong idea–these features are far from being fully explained. But a briny water would fit the aforementioned characteristics nicely. The saltiness would lower the water’s freezing point such that it could flow even during the cold (relative to Earth) Martian spring and summer. And we already know that brines were abundant in Mars’ past, making them a much more likely candidate to make these dark features rather than something wholly new.

But mysteries still abound. For one, the markings aren’t dark because they are wet, but because of something else at play here that is currently unexplained. Equally inexplicable: why the features brighten again when the temperatures decline in fall and winter.

But the finding is no less significant for the questions it raises. Liquid water on mars, salty though it may be, is a huge finding for those holding out hope that Mars might yet yield some kind of evidence of life. And even if it doesn’t, perhaps it could help sustain life–perhaps life forms visiting from another nearby planet–at some point in the future.

Oxygen Molecules in the Orion Nebula

Astronomers are finding more and more of life’s key ingredients in deep space, from amino acids to a huge water reservoir, and now molecular oxygen.

Teams working with the Herschel Space Telescope have confirmed finding O₂ in the Orion nebula, the first time scientists have been able to pinpoint the crucial yet simple molecule.

Oxygen is the third-most abundant element in the universe, so surely its molecular form is abundant in space, said Bill Danchi, Herschel program scientist at NASA, in a news release. Individual atoms of oxygen are very common, especially around stars, so it’s sort of odd that scientists have not been able to find large quantities of O₂. They have been using balloons and space- and Earth-based telescopes to hunt for it, but to no avail.

Now Danchi, Paul Goldsmith and other NASA scientists have a new paper that may explain where the O₂ is hiding — locked up in water ice that coats interstellar dust. They found some O₂ in the Orion star-forming region, where starlight probably warmed the dust and released water, which was then converted into oxygen molecules.

The Herschel Space Observatory’s large viewing area and powerful infrared detectors were able to detect the O₂.

But the researchers didn’t find very much of it, and still can’t explain where the rest of it is. “The universe still holds many secrets,” Goldsmith said.

Molecular oxygen makes up about 20 percent of the air we breathe on Earth, and is a crucial ingredient for metabolism throughout the animal kingdom. If life forms in other places resemble life forms here, then they, too, might require O₂.

Goldsmith and colleagues plan to keep looking for more O₂ in other star-forming regions.

Lurking in a distant supermassive black hole there exists a reservoir of water as big as 140 trillion oceans, the largest repository of water in the universe and 4,000 times more than exists in the Milky Way. Two teams of astronomers discovered this mass of water 12 billion light years away, where it manifests as vapor spread across hundreds of light years.

The reservoir was found spread around the gaseous region of a quasar, a luminous compact region at the center of a galaxy and fueled by a black hole. This discovery shows that water can be found throughout the universe, even early on. While that is not necessarily news to scientists, water has never been found this far away before. The light from the quasar (the APM 08279+5255 quasar in the constellation Lynx, to be exact) took 12 billion years to get to Earth, meaning that this mass of water existed when the universe was only 1.6 billion years old.

Beginning observations in 2008, one group used a tool called Z-Spec at Caltech Submillimeter Observatory in Hawaii and the other used the Plateau de Bure Interferometer in the French Alps. These instruments observe millimeter and submillimeter wavelengths which allow for the discovery of trace gases (or huge reservoirs of water vapor) in the early universe. The detection of several spectral signatures of water in the quasar gave researchers the information needed to determine the enormous size of the reservoir.

Fragmented human genomes could be shipped toward the stars and reconstructed upon their arrival, spawning the first interstellar citizens and avoiding the problems of long-distance space survival.

That’s just one idea — proposed by genome pioneer J. Craig Venter — emerging from the field of dreams seeded by DARPA’s 100-Year Starship project. DARPA is collecting proposals for a conference on the starship project this fall.

We have no idea what interstellar travel might look like in 100 years, of course — just as Jules Verne could never have conceived of the technology required to really send humans to the moon when he wrote about it in 1865. But if we start now, we can make it happen, according to David Neyland, who directs DARPA’s Tactical Technology Office.

“One hundred years is a pretty good period of time in terms of inspiring research to go off and tackle really hard problems that you don’t even know which questions to ask at the beginning,” he said in a conference call Thursday.

Neyland approached Pete Worden, director of NASA’s Ames Research Center, last fall and the two talked about how to spur a starship project. The goal is not necessarily to build a spaceship, Neyland explained, but rather to spur the monumental technology advances that would be required for such a feat. So the 100-Year Starship is more like a thought experiment than a construction project.

“One hundred years from now, there will be capabilities coming out of this that benefit us in the Department of Defense and the civilian sector, but also give us the capabilities of building the starship if we chose to do so,” Neyland said.

So now DARPA is soliciting ideas for the types of questions that would need to be addressed for this to happen, from the practical to the fantastical. Along with the physics behind concepts like time dilation, DARPA wants people from all walks of life to raise questions — from the moral and ethical implications of leaving forever, to the energy, agricultural and medical requirements involved, to political and legal considerations.

DARPA held a workshop in January and invited a host of science fiction authors, physicists, biologists and other thinkers, who all posed questions about a hypothetical journey to the stars. That’s where Venter’s genome proposal came up, Neyland said.

DARPA took that group’s questions and solicited a request for information, which we told you about back in May. Those proposals were due June 3, and now DARPA is synthesizing them into a formal request for proposals, which will be unveiled at a conference Sept. 30-Oct. 2 in Orlando. After that, DARPA will award a contract, worth around $500,000 depending on several factors, for some kind of entity that will take over the next 100 years of planning. The winner doesn’t have to be from the U.S., and DARPA is noncommittal on whether it would be a non-profit or for-profit venture.

“The crux, to us, is inspiration of research — not just in solving the physics-based problems. It’s across all of the domains,” Neyland said.

Since the project first emerged last fall, when Worden described it at a speech at Singularity University, Worden and Neyland have received several calls from people who want to lend money to the effort. Neyland wouldn’t say who, but he said he’s told these would-be interstellar investors they should consider writing a proposal.

Neyland said he could only imagine the benefits that could come from planning an interstellar ship. NASA probably didn’t envision a market for cordless power tools when it first built them for the moon missions, for instance.

“Those unpredictable and ancillary things go back into the Department of Defense as well as the commercial sector and the public sector, and benefits all of us,” he said.