RENEE MONTAGNE, host:
This is MORNING EDITION, from NPR News. I'm Renee Montagne.
LINDA WERTHEIMER, host:
And I'm Linda Wertheimer.
This week, we're looking back at significant developments of 2010 in the world of science - or perhaps we should say in the otherworldly field of astronomy, which had a record-breaking year. Scientists found more than 100 new planets, more than ever before. And a few of the planets look enticingly like our own cozy Earth.
NPR's Dan Charles reports.
DAN CHARLES: Twenty years ago, nobody knew if there were planets outside our solar system. Today, we have a list of more than 500 such exoplanets. This past year, researchers announced they'd found whole solar systems with three, five, or maybe even seven planets.
2010 also brought us the first discoveries from NASA's official planet-hunting instrument, a telescope in space called Kepler. The Kepler team has announced just a handful of new planets so far. But there are hints of hundreds more. But don't try to tell Marc Kuchner that discovering planets has now become routine. Kuchner is an astrophysicist at NASA's Goddard Space Flight Center.
Dr. MARC KUCHNER (Astrophysicist, NASA's Goddard Space Flight Center): You could say giving birth to babies is routine, right, in the sense that it happens all the time. But if you're the person who found the planet, it's not routine for you. It's still - you know, my heart skips a beat every time I hear about one of these things.
CHARLES: Because finding a new planet still feels like science fiction becoming fact. Those distant balls of gas or water or rock represent the possibility of other worlds, other civilizations. And this year, for the first time, scientists say they found a planet just far enough from to its star that liquid water could exist there.
Dr. KUCHNER: Finding a planet like ours is exactly what got me into this game. I want to find out - I don't just want to find a planet like ours. I want to know the answer to the question: Are we alone?
CHARLES: Now, don't expect an answer to that question anytime soon. Most of these planets still are invisible. We only know they exist because they change the light from their stars in subtle ways. For instance, if the light from any star dims slightly in a regular pattern, every few days or years, it's a signal that a planet is orbiting that star, blocking a bit of the light every time it passes.
Astronomers can then calculate how big the planets are and how far they are from their star. Also, when the planet comes between its star and us, a tiny fraction of the star's light passes through the planet's atmosphere, like a sunrise or sunset around the edge of the planet.
Dr. KUCHNER: And that light, we can analyze and we can use it to tell us something about the chemistry of the atmosphere.
CHARLES: Is there oxygen there? Methane? Ammonia?
Dr. ALYCIA WEINBERGER (Astrophysicist, Carnegie Institution of Washington): That is a whole new era in planet science.
CHARLES: Alycia Weinberger is an astrophysicist at the Carnegie Institution of Washington.
Dr. WEINBERGER: There's been just a tremendous number of papers that have come out in the last year, and even before that, on trying to characterize what planets are really made out of.
CHARLES: Also, it is now possible to see a few distant planets directly. Astronomers can create a kind of artificial eclipse of a star inside a telescope. And then sometimes planets come into view - faint dots moving around the star. What all these techniques reveal is a shocking amount of planetary diversity. Again, NASA astrophysicist Marc Kuchner.
Dr. KUCHNER: There are planets that are similar to things that we have in the solar system. There are planets that are so different, we didn't dream of them. I mean, we literally just didn't think of them, that there could be such crazy things out there.
CHARLES: A planet turned up recently with an atmosphere rich in carbon. On a planet like that, diamond might be as common as rocks are here. Astronomers used to think that planetary systems had a natural order, with small planets like Earth close to the star and stately gas giants like Jupiter far away. But then they found lots of huge planets right next to their stars, zipping around in super-fast orbits.
Dr. WEINBERGER: So that is still a real puzzle.
CHARLES: And Alycia Weinberger says figuring out how such planets formed is just the kind of puzzle that scientists love.
Dr. WEINBERGER: You know, fields in which there's nothing left to figure out are really no fun at all. And I think the exoplanet field has been attracting lots of really bright, young people because there are these interesting problems to solve.
CHARLES: They're also looking forward to using a powerful new tool. NASA is building a big, new space telescope a hundred times more powerful than the famous Hubble Space Telescope. Astronomers get a kind of dreamy look in their eyes just talking about it. So for them, it was probably the worst news of 2010 when NASA announced in the fall that its dreamboat telescope was going to cost one and a half billion dollars more than expected. The agency has not said how it will cover the cost overrun, or whether it still hopes to launch the telescope within five years.
Dan Charles, NPR News, Washington.�