Earth-like water found on a comet has led scientists to conclude that comets were probably responsible for delivering water to our planet billions of years ago, and thus creating life.
The revelation began last November, when the Deep Impact/EPOXI spacecraft flew by the small comet Hartley 2, which comes from the distant Kuiper Belt out past Neptune.
An international study led by Paul Hartogh at the Max Planck Institute for Solar System Research in Katlenburg-Lindau, Germany, found that Hartley 2's water is chemically very similar to water on Earth.
The BBC reported that astronomers using the Herschel space telescope measured the fraction of deuterium, a rare type of hydrogen, in the comet's water.
Just like the Earth's oceans, the water contained half the amount of deuterium than seen on other comets, suggesting that some of Earth's water comes from the same comet family.
Comet Hartley 2 is reportedly the first "Kuiper Belt" object to undergo the deuterium analysis.
Hartogh, who's findings were published Wednesday in the journal Nature, said prior studies suggested the early Earth was dry, lacking water and other volatile materials.
When the Earth formed it was so hot that most volatiles escaped to space, so when the Earth cooled down it was dry.
Water and other volatiles must have been delivered at a later stage.
The ANI news agency reported that asteroids, which are found mostly in a band between Mars and Jupiter, were previously thought to have been the major depositors of water to earth.