Water on Earth: Asteroids!?

There has always been much speculation over how Earth has always contained water. However, there is definitely a scientific truth: During the formation of the solar system, scientists know that the space was mostly permeated by hydrogen gas. When the Sun was forming, it generated a lot of heat, and this resulted in spherical distributions of temperature ranging from extremely hot to extremely cold, as a function of radius. Because of this, scientists can define boundaries where metals, rocks, ice and water could condense out of the hydrogen gas at certain temperatures! This is why, at present day, we can see how the inner solar system is composed of solely rocky planets, and past the asteroid belt in the outer solar system, there are jovian planets which are all mostly gas.

Now that there is proper context, it makes sense that water could not have condensed in the inner solar system, simply because it was too hot and the water would have vaporized. However, there is no problem with water condensing in the outer solar system. Here lies the basis of the water-comet theory: When the solar system was still early in its age and gravitational interactions were forcing collisions between bodies, an H2O-abundant comet reached Earth and crossed its orbital path, thus colliding with it. It also could have been multiple asteroids that delivered the goods, but regardless, the result is the same and the reasoning is sound. The purpose of this post is this: recently, new evidence for asteroids carrying water in other star systems has solidified the theory's ideas. "In observations obtained at the William Herschel Telescope in the Canary Islands, the University of Warwick astronomers detected a large quantity of hydrogen and oxygen in the atmosphere of a white dwarf (known as SDSS J1242+5226). The quantities found provide the evidence that a water-rich exo-asteroid was disrupted and eventually delivered the water it contained onto the star." This is profound because it proves that other systems also have asteroids that carry high volumes of water, and it most likely isn't a single case!

For more information: http://phys.org/news/2015-05-fresh-evidence-earth-asteroid-debris.html?utm_source=menu&utm_medium=link&utm_campaign=item-menu