How did the Earth get its oceans? The primordial Earth was a seething ball of magma, so the water that it began with would have evaporated into space. As a result, planetary scientists have long debated which of two types of objects, comets or asteroids, were more responsible for delivering Earth’s water.
The ice on 24 Themis appears to have been present for billions of years. Researchers suggest that an icy reservoir within the asteroid may continually replenish the surface frost. This find is prompting astronomers to hypothesize that an asteroid collision with early Earth might explain how water was delivered to our planet.