It's amazing to think that just a few years ago we had no clue about planets around other stars. Now we know of over 300, and we're getting an idea of how they form, where they form, how they behave, and whether there's a chance of any being like home, our home. Not only that, we're learning whether they can form around stars that are different than the Sun: more massive, less massive, hotter, cooler, whatever. And new Spitzer Space Telescope results show that when conditions to form planets are different, the chemistry is different as well.
Artist's view of a planet forming around a cool star. Note the dark disk partially covering the star.
Planets form from disks of rock, metal, and ice surrounding young stars, accreting material much like a snowball rolling down a hill. When they get big enough from random collisions, their gravity takes over, pulling ...
