Click the image to see the Discovery.com story on one asteroid's water plume.
|In the solar system's infancy, after the planets, asteroids and smaller bodies had formed, we didn't see gentle, circular(-ish) orbits as we do today for most major bodies. Since the 1980s, astronomers thought the Asteroid Belt formed where it lives today, a loose formation between Mars and Jupiter, a loose scattering of rock and dust that simply failed to form into a planet. However, astronomers have been studied a lot of asteroids since that time, some close-up using robotic missions like NEAR-Shoemaker. We have now learned that things weren't always as they are now, and that violence and randomness ruled the early Solar System.
"What we're leaning toward now is that asteroids, rather than forming in the asteroid belt, formed throughout the entire solar system... as close to the Sun as Mercury and as far away as Neptune, and then, through the planetary migration, you scatter them all over the place. What's left is what you see in the asteroid belt today," says astrophysicist Francesca DeMeo. The new theory is that the asteroids now residing in their Mars-to-Jupiter prison had once flown free throughout the Solar System, free to pummel planets, hurtle to a fiery death in the Sun, careen off into deep space on their own. Wildly orbiting planets launched these smaller bodies hither and yon. How crazy were these early planetary dances? It now appears that Mars might have visited Earth's realm - which also explains why we regularly find Mars meteorites on Earth - and mighty Jupiter's orbit once dipped as close as Mars' current locale. All this random chaos meant that little guys like comets and asteroids had no say in where they lived, and the Big Guys like Jupiter really were the gods who controlled the lives of billions of little guys populating the Solar System. The Old Gods might even be responsible for life on Earth, seeding our planet with water by hurtling comets and other icy bodies at us, plus carbon compounds from carbonaceous asteroids. I can see the headline: "Science Proves Life Came from the Gods!"
Click this thumbnail to see the full-size asteroid infographic.
Sure, now Lord Jupiter is happy to maintain a stately, near-circular orbit, maintaining a gravitational fence around the wild ones penned in the Asteroid Belt (Lord Mars keeps the other gate shut), but in their youth they were unpredictable gods, much like their namesakes.
Had to share this little bit of Astro-Awesomeness. I'll leave you with this lovely image of dwarf-planet Ceres (formerly known as "asteroid Ceres," but now a peer of Lord Pluto):
Click the image to see the Wikipedia article on Ceres.
PS: It now appears that Ceres - which makes up about 1/3 of all the asteroid-ish mass in the Solar System - is habitable; that is, is giving off a plume of water vapor. This place has a water-rich atmosphere!
These discoveries... I tell you what: We live in amazing times.