This was the decade of the first face transplant, the first extinct species brought back from the dead, and printable human tissue; a decade that brought us closer to synthetic life forms and the invisibility cloak. But we've whittled it down to ten of the decade's biggest science stories, with discoveries, advances, and topics that are sure to change our lives in the next ten years.

It's Full of Planets: This was a big decade for planets, and not just because Pluto got a downgrade. In 2005, astronomers discovered Eris, a dwarf planet larger Pluto (as well as smaller dwarf planets Haumea and Makemake). Eris' discovery prompted the International Astronomical Union to actually define the term planet, leading to Pluto's demotion to dwarf planet. But the discovery of Eris after all this time suggests there is still a lot to learn about our solar system.

We also got our first direct look at exoplanets, worlds outside our solar system, thanks to the Hubble Telescope. In 2008, astronomers at the Keck and Gemini captured the first images of planets orbiting distant stars. And the planetary discoveries just keep getting more exciting; just this week, astronomers announced that they had observed a super-Earth that might be made largely of liquid water.

Water, Water Everywhere: The world watched on as the Phoenix Lander dug through the Martian terrain for signs of water on the Red Planet. In the summer of 2008, NASA announced it had found definitive proof of water ice on Mars. More recently, scientists discovered that large deposits of water ice exist beneath the planet's surface. This fall, the moon became the center of our watery attention when astronomers found evidence of water throughout the moon's surface. Although the supervillainous plot to bomb the moon didn't seem as initially impressive as we had hoped, the probe did confirm researchers' suspicions that the moon does, in fact, contain a significant amount of frozen water. These discoveries not only reveal more about our solar system, they indicate that, should humans try to colonize Mars or the moon, there will be resources to make survival a little easier.

Shaking Up the Human Family Tree: Humanity got a new great-great-grandmother (or perhaps she's our great-great-great-aunt) in Ardi, a fossilized hominid skeleton found in Ethiopia. Granted, Ardipithecus ramidus was discovered in 1992, but it wasn't until 2009 that she was revealed as a significant addition to our family tree. Although there's technically no "missing link" because humans didn't evolve from chimpanzees, Ardi is, so far, our closest link to chimps, and brings us closer to the common human-chimp ancestor than ever before. Analysis of Ardi's skeleton and probably anatomy reveals just how unlike either chimps that common ancestor is bound to be. One of the Ardi researchers even quipped that when we find that common ancestor, it might look less like we evolved from a chimp-like creature and more like chimps evolved from creatures more like us.

The Book of Life Recorded: Our understanding of human genetics reached a new milestone with the mapping of the human genome. The Human Genome Project announced a rough draft of the human genome in 2000, followed by a more complete version in 2003; the sequence of the last chromosome was published in 2006. Though the genome hasn't been 100 percent mapped, the Human Genome Project has completed its mapping goals. We still have to interpret the sequences we have recorded, but hopefully as we translate the book of our genetic lives, we will get a better understand of how our genes interact and improve our treatment of genetic diseases. Plus, the project has paved the way for sequencing other critters and plants, and, just this week, the lung cancer and melanoma genomes were sequenced.

Changing Your Genes: The promises of genetic engineering have really begun to bear fruit in the last few years, in ways far beyond Alba, the glowing transgenic bunny that grabbed headlines in 2000. In 1999, an 18-year-old with a, inherited liver disease died during a gene therapy trial, after suffering an unanticipated immune reaction to a viral vector. But in more recent years, gene therapy and genetic engineering have shown their promise. In 2000, scientists reported the first gene therapy success, having provided a patient with severe combine immunodeficiency (commonly known as "Bubble Boy" syndrome), though SCID gene therapy treatments were halted when patients developed leukemia. This year, gene therapy successfully treated children with a congenital form of blindness, giving them the ability to see for the first time in their lives. Meanwhile, genetic engineering experiments on animals have cured color blindness in monkeys, created super-strong monkeys, created drug-producing rats, and enabled animals to pass their altered genes to their offspring.

Stem Cells Grow Up: Embryonic stem cells have been a source of contention for years, but in 2007, Shinya Yamanaka helped sidestep that issue when he found a way to reprogram adult skin cells into induced pluripotent stem cells. Stem cells themselves have continued to aid important medical advances. In 2008, researchers generated motor neurons from elderly patients with ALS, an advance that could help researchers better understand the disease. A newly released study has suggested that a mini stem cell transplant could reverse sickle cell disease, and stem cell research has lead to advances in HIV research and the treatment of heart disease.

Climate Change Takes Center Stage: One of the biggest science stories of the decade has been less about scientific advances than about how the public responds to scientific research. Reports that the glaciers are melting faster than expected, a decade of record warmth, and Al Gore's Nobel Prize have all been part of the conversation on climate change and to what extent humans are responsible.

Commercial Spacecrafts Prepare to Take Flight: Amidst NASA budget cuts, commercial spaceflight has come to the forefront. The Ansari X Prize, first offered in 1996 for the first private enterprise that could fly a three-passenger vehicle 100 kilopmeters into space twice in one week. In 2004, the prize was finally won by Mojave Aerospace Ventures' SpaceShipOne. That same year, Virgin Galactic was founded to further space tourism. The company recently unveiled SpaceShipTwo, the first commercial spacecraft. 2004 also saw the certification of the Mojave Air and Space Port, the first licensed facility for horizontal launches of reusable spacecraft in the US. In anticipation of the spaceflight business, one company claims it's readying a space hotel.

Our Cyborg Present: In the last decade, humans and machines have gotten closer than ever. We have machines that can read our memories, computers that let us type with our brains, and robotic arms controlled by monkey minds. Perhaps the most impressive cyborg advances have come in the last few months, with researchers hooking amputees up to robotic arms that not only respond to electrical signals from the human brain, but also provide tactile feedback.

The LHC Comes Online: The Large Hadron Collider has just begun colliding proton beams, but its construction represents one of the most ambitious scientific undertakings ever. The immense particle accelerator will hopefully give us first-hand observations of aspects of the universe that have been, thus far, the realm of theoretical physics. Despite fears from doomsayers that the LHC would destroy the world and a series of mishaps that led to claims that the device was being sabotaged from the future, the LHC came online this year and quickly got to smashing protons at record-breaking speeds.

COROT-7b revolves around the star COROT-7, 500 light years from Earth. Its diameter is twice that of our planet, and its temperatures are rather extreme. Its orbit falls so close to COROT that COROT-7b's average daily temperature is 2,000 degrees Celsius, and negative 200 at night.

According to Wired Science:

Whipping around [its sun] at a record-breaking speed of 750,000 kilometers per hour, the planet's extreme environment may include lava or boiling oceans on its surface. Because this is the first exoplanet of its kind, researchers don't know quite what to expect.

Though our Earth-centric, carbon-centric, biology-centric scientists think that rocky planets are more likely than gas giants to support life, COROT-7b has them shaking their heads. Apparently the intense temperature shifts and boiling oceans aren't good for developing life. But COROT-7b has a sister planet, COROT-7c, that might be more habitable.

In the end, what this discovery tells us is that rocky planets aren't terribly unusual in the universe. Of course if Iain M. Banks' scenario in The Algebraist is correct, and the greatest civilizations thrive only on gas giants, this really doesn't do us much good.

via Wired Science

Image of COROT-7b via ESO/L.

In nearly every other observed planetary system, the planets spin around the star the same direction as the star itself is spinning. This is because, scientists believe, both the stars themselves and their planets are formed from the same rotating gas clouds, leaving them all spinning in the same direction as that original cloud.

There are exceptions to this general rule, but those are caused by gravitational interference pushing the planets into orbits at very strange angles. A brush with another planet or large gravity source can cause the aligned orbit to push into a strange angle. And the team that discovered this strange new planet, dubbed WASP-17b, wanted to blame this mechanism again.

But gravitational interference might be a bit of a stretch here: the planet's orbit is 150 degrees opposed, or almost directly opposite, the star's rotation. It'd take a pretty significant gravitational shove to get this much of a difference.

WASP-17b is notable for a couple of other reasons, too, all described in a paper submitted to the Astrophysical Journal. WASP-17b is possibly the largest yet discovered exo-planet, at twice the width of Jupiter. It's also pretty light, at only half of Jupiter's mass. That leaves the planet with a consistency similar to polystyrene, a light, puffed up ball of mostly nothing.The research team thinks this might be an effect of its very close (7 million kilometers), very quick (only 3.7 days) orbit yanking materials around inside the body and deforming it into this weird puffy planet.

The planet is, to say the least, really strange, compared to what scientists have seen before. But such discoveries remind us that we've only seen a very, very small percentage of what exists in the rest of the universe. Maybe what we have deemed to be "normal" isn't normal, but just what we are used to.

Planet found orbiting its star backwards for first time [via NewScientist]
Paper: WASP-17b: an ultra-low density planet in a probable retrograde orbit [arXiv.org]

(Illustration: what such a close-orbiting planet may look like, from ESA/C. Carreau)

In 2004, a group of scientists at the Isaac Newton Telescope, on the Spanish island of La Palma, noticed "an uneven microlensing event" from the Andromeda galaxy. As New Scientist explains, microlensing is when "a distant source star is briefly magnified by the gravity of an object passing in front of it"; at the time, the 2004 event was thought to be a binary star, but new computer simulations created by a team led by Philippe Jetzer of the University of Zurich - one of the scientists who discovered it - are suggesting otherwise:

[A]ccording to the new simulation, the lensing pattern fits a star with a smaller companion weighing just 6 or 7 times the mass of Jupiter. "It plausibly could be a planet," says Andrew Gould of Ohio State University, who was not part of the team. The matter will probably not be settled, since lensing events occur randomly and do not repeat themselves, and for the foreseeable future, other techniques will be unable to detect planets beyond the Milky Way.

Goddammit, science. Why haven't you invented FTL space travel yet, so we could find out whether or not we really have discovered planets next door already?

First extragalactic exoplanet may have been found [New Scientist]

Steven Pravdo and Stuart Shaklan of NASA's Jet Propulsion Laboratory led the twelve-year effort responsible for discovering the exoplanet, which has been designated VB 10b after its star, VB 10. The red dwarf star, roughly a twelfth the size of our sun, is just twenty lightyears away, making it one of the closest stars with an exoplanet. VB 10 is also only one of a handful of red dwarfs with confirmed exoplanets.

VB 10b is the first planet discovered using the astrometry method. It works on the principle that a planet does not exactly orbit its star. Instead, both celestial bodies orbit around their common center of gravity, although in most cases the huge mass disparity between the two makes their center of gravity and the star itself practically the same thing, which tends to reduce this method's effectiveness. For instance, alien astronomers would almost certainly be unable to detect any of the planets around our sun using the astrometry method.

This particular exoplanet, however, was pretty much the perfect candidate to be found using this method. Six times the size of Jupiter, VB 10b is nearly as massive as the star, greatly exaggerating the star's motion around their center of gravity. It's also relatively distant from its sun, which again causes the red dwarf to trace an unusually large arc around its center of gravity. Finally, its close proximity to our solar system made it far easier to detect VB 10's exoplanet-induced motion.

Even with all those favorable conditions, it still took Pravdo and Shaklan twelve years searching through thirty different star systems to find conclusive evidence, and even then their discovery was, as New Scientist puts it, "equivalent to measuring the width of a human hair from a distance of about 3 kilometres." This is pretty much why I find exoplanet-hunting the most awesomely absurd endeavor in modern science.

The long-awaited success of the astrometry technique provides astronomers with a way of locating planets that are relatively far away from their stars. The most successful technique for finding exoplanets is to locate shifts in the star's light spectrum that indicate an orbiting planet is causing the star to wobble. This is known as the radial velocity technique. Another method is to find variations in the star's brightness as a planet passes in front of it relative to our vantage point. Both of these work best when the exoplanet is close to the star it orbits.

VB 10b is, in absolute terms, actually pretty close to its star, as it's roughly the same distance from VB 10 that Mercury is from our sun. However, the tiny mass of the star makes its distance more comparable to that of Jupiter in terms of the warmth it receives and the gravitational effects that act upon it. This actually opens up the possibility of rocky inner planets between VB 10 and VB 10b. Such planets might be detectable with Europe's wonderfully named Very Large Telescope, which could use the radial velocity technique to search for them.

The planet's discovery could also change our understanding of what sorts of stars can have planetary systems. Red dwarfs are by far the most common kind of star, comprising roughly seventy percent of all stars. As more and more exoplanets are discovered around red dwarfs - and the massive size of VB 10b relative to VB 10 suggest such stars can support pretty much any kind of planet - the evidence mounts that planets are far, far more common that once was thought.

[NewScientist]

The planet Fomalhaut-B orbits the star Fomalhaut, and it's a balmy 260 degrees (Fahrenheit), cooler than other exo-planets. And meanwhile, Lawrence Livermore researchers believe they've snapped pics of three other exo-planets, in the Pegasus constellation. Click through for more pics.

That giant red ring, by the way, is a 21.5 billion mile debris disk surrounding Fomalhaut, which is Arabic for "mouth of the fish." The planet is a white speck over towards the right.

The three Pegasus planets are orbiting the star HR 8799, which is just barely visible in the night sky using binoculars. The Lawrence Livermore crew had found these planets in 2007, but waited to confirm their findings. Like Fomalhaut-B, the other three planets are gas giants, but they're way hotter than Fomalhaut-B. None of these planets is likely to support life, at least as we understand it. Here's an infrared picture of HR 8799 that shows its planets:

And here are some more pics of Fomalhaut-B, including a porny artist's impression.

[Hubble and AP and Science News]

How many extrasolar planets have we found so far? 287 (as of April 1, 2008).

When was the first one found? Between 1988 and the early 1990s, several astronomers claimed to have found extraslar planets. However, the first confirmed planet was found in 1992, and the first orbiting a normal (non-pulsar) star was found in 1995.

Which one is closest to Earth? Epsilon Eridani b is a gas giant a little smaller than Jupiter that orbits a star 10.4 light years from Earth.

Which one is most likely to support life? Gliese 581 c is the smallest exoplanet found so far, and it orbits within the "habitable zone" of its star.

What is the largest planet? GQ Lup b has a mass of more than 21 Jupiters, or 70 percent of our sun's mass. In fact, there is some debate whether it is a planet or a brown dwarf star in a companion orbit to GQ Lup itself.

How do we detect extrasolar planets? It's almost impossible to find them by looking through a telescope - not because they are small, but because the contrast between the brightness of the star a planet orbits and the planet itself is too great for us to pick out the planet. We can measure the gravitational wobble induced in the star by the planet by looking at the shift in wavelength of light coming from the star (the Doppler effect) or we can examine the "gravitational lensing" effect produced when light from a background star passes through the distant solar system. In rare cases, a planet transits in front of its star (in relation to our point of view), allowing us to notice the dimming of the star.

What can we learn from these methods? By combining the data and doing some serious physics calculations, astronomers can figure out the mass and density of the planet and the characteristics of its orbit. We can even learn something about the composition of the planet and its atmosphere - the Hubble Telescope was able to detect methane in the atmosphere of a gas giant earlier this year.

Have we found any Earth-like planets? No. The majority of extrasolar planets found so far have been gas giants. We have found a few "terrestrial" planets, denser than gas giants, but they have all had five or more times the mass of Earth. Astronomers call them Super-Earths. Image by: NASA.

Extrasolar Planets. [Nature]

PlanetQuest: Exoplanet Exploration. [NASA]

Most of the 280 or so exoplanets discovered so far have been searing gas giants that orbit their stars closer than Mercury is to the Sun. But GJ 436c is the latest in a growing class of rocky exoplanets called 'super-Earths' that are getting smaller by the day, thanks to a new method planet-hunting astronomers are using to measure stars' gravitational wobble:

Ignasi Ribas, lead author of the study from the Spanish Research Council (CSIC), says: "After final confirmation, the new exoplanet will be the smallest found to date. It is the first one to be identified from the perturbations exerted on another planet of the system. Because of this, the study opens a new path that should lead to the discovery of even smaller planets in the near future, with the goal of eventually finding worlds more and more similar to the Earth."

Photo: Wikipedia