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Marc Kuchner: I don't know--when I was growing up, there was no such thing as planets around other

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stars. If you were to talk about it at a scientific meeting, people would laugh at

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you. Not that I was talking at scientific meetings when I was in high school, but

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so I'm told.

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Jennifer Wiseman: Planets are very small compared to the stars that they orbit. They're also very dim.

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Marc Kuchner: For example, the Earth is ten billion times fainter than the Sun--ten billion times fainter.

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Jennifer Wiseman: It's kind of like trying to see a firefly next to a lighthouse. It gets lost in the glare.

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Marc Kuchner: The Hubble Space Telescope takes pictures of nearby stars and uses a

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special tool called a coronagraph and the coronagraph blocks out the light from the star.

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Aki Roberge: It's a fancy way of putting your thumb over the star,

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basically, so you can see something faint that is right next to it.

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Jennifer Wiseman: We can also use Hubble and other telescopes to study regions

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where we think planets might be forming.

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Marc Kuchner: We see in images from Hubble, we see these rings of dust around nearby stars.

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Aki Roberge: Well what I observe with Hubble are those disks.

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Those disks of gas and dust around the young stars, in which we think the dust

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grains are starting to clump together and build up into pebbles, rocks, asteroids, comets, Earths.

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Jennifer Wiseman: We're finding baby solar systems by using Hubble and other telescopes, including sort of

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ground-based radio telescopes that can peer into these disks around stars and

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see young planets or regions where young planetary systems are forming.

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Aki Roberge: You know, the study of exoplanets is only a little over 15 years old.

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Marc Kuchner: We've discovered more than 400 extrasolar planets now.

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Aki Roberge: You know, we're still just beginning to understand how the processes

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that formed our own solar system, also formed these really diverse types of planets.

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I think the thing that excites me most is just the basic discovery of what exists. You know, what's out there.

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Waterworlds, carbon planets? It sounds like science fiction, but not really. Not anymore.

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Marc Kuchner: Why did life arise on Earth instead of somewhere else?

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I mean if there's another planet that could have life on it, why aren't we there?

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