Asteroids and comets are the most likely source of Earth’s water according to the discovery of an asteroid that was rich in water near a white dwarf star that is 33,900 light-years away from Earth. The water that was originally in the asteroid had been vaporized by the gravity and heat of the star.
The astronomers used the William Herschel Telescope to analyze the atmosphere around the white dwarf star known as SDSS J1242+5226. The quantities of hydrogen and oxygen were comparable to the quantities that would exist in water. The relative positions of the gases in the star’s atmosphere also indicate that the water was deposited by an asteroid that was laden with water and flying free in the universe. Stars contain helium and hydrogen naturally but oxygen in a star is very rare.
The asteroid that delivered the water to SDSS J1242+5226 was estimated to be 900 kilometers in diameter. The water content was the equivalent of between 30 percent and 35 percent of the amount of water presently on Earth. This is the first proof that water is deposited by asteroids and comets on other planets and stars in the universe.
The discovery lends validity to the theory that Earth was a dry planet when it was relatively young. The water on Earth came from comets and asteroids that hit the Earth over an untold number of years. The water that was delivered to Earth was fresh water. The oceans of Earth formed from the dissolving of solid salts on the Earth’s surface.
Astronomers have known that comets and asteroids that contain large quantities of water are common throughout the known universe. The new discovery shows that it is possible for Earth’s water to have come from space via asteroids and comets. This is the first known absolute proof that the event is possible and most highly probable.