The mystery of how water was able to survive Earth's fiery past has always baffled scientists. Earth had been a very hot planet and any water would have simply evaporated. A European team of astronomers may have the answer to the age-old riddle with a discovery of a reservoir of water vapor in space.

The discovery made by the European Space Agency's orbiting Herschel observatory could explain how water made its way to Earth all those billions of years ago. The star named TW Hydrae located about 175 light years from Earth has enough water vapor to fill Earth's oceans several thousand times.

"Our observations of this cold vapor indicates enough water exists in the disk to fill thousands of Earth oceans," said astronomer Michiel Hogerheijde of Leiden Observatory in the Netherlands.

"Scientists have long suspected there were these reservoirs of cold water vapor hiding in the outer regions of planet-forming disks, but until now we've only found signs of water vapor in hot regions closer to the suns," Hogerheijde, the lead author of the study said in an interview. "Since the comets and cold asteroids are formed in the outer reaches, this was a problem for the theory that comets delivered the water to Earth. But now we have the cold reservoir in the region where comets are formed, and so the theory gets considerably stronger."

The study which will be published in the October 21 issue of the scientific journal Science states that the discovery supports the theory that Earth's waters came from an extraterrestrial source, namely from comets hitting the young Earth.

TW Hydrae has water vapor in the edge of its planet-forming disk. This region is where comets and giant planets are believed to form and since the star is much like how the Earth was formed 4.5 billion years ago, the scientists believe this scenario was how water was delivered to Earth. The all-important H2O was delivered to Earth via comets and asteroids. It could also mean that there are other planets that have water throughout the galaxies through this cosmic courier.

The water vapor detected in TW Hydrae is only a small portion of the "ice reservoir" in the region. There are still ice crystals in the region that remain undetected.