Discovery of water-rich asteroid may mean life exists outside solar system
An icy asteroid was eaten by the remains of a dead star 150 light years from Earth, say Dr. Jay Farihi of the Cambridge Institute of Astronomy and Dr. Boris Gänsicke of the University of Warwick. This discovery, made by using the Hubble Space Telescope to identify elements in the debris surrounding the GD 61 white dwarf star was published in Science, and represents the first evidence of both water and a rocky surface being found together outside the solar system.
Why is that important? Because the combination, ice + rocky surface, is necessary for the formation of potentially habitable planets.
The asteroid, which is at least 56 miles wide and possibly much larger, could be similar to objects that delivered water to Earth in its early history. The earth is only .02% water by mass, and much of that was most likely delivered by comets and asteroids. And the discovery of a water rich asteroid leads scientists to believe that a similar process could have happened in the GD 61 system. In a BBC interview, Dr. Jay Farihi revealed that the system likely had planets.
“Having asteroids and no planets is logically possible but it’s very likely physically implausible. So, we know there were rocky planets [in GD 61] because we can see the rocky building blocks; and we know there was the potential to deliver water to their surfaces because we’ve seen at least one very water-rich and large asteroid.”
The scientists discovered this by examining the ultraviolet light emitted by GD 61, which gave them clues about the elemental makeup of the star’s debris. They found elements like magnesium, silicon, and iron, which are prevalent in rocky asteroids. They also found an overabundance of oxygen — so much oxygen that scientists believe the asteroid was a full 26% water.
The discovery is also interesting because it gives us a peek into what alien astronomers might see in the remains of our own solar system, billions of years from now. They’d see the remains of planets and water rich asteroids surrounding a white dwarf star. Perhaps they would wonder if the solar system had the potential for life like them.
And the planets those hypothetical alien astronomers might gaze at us from might not be as rare as once thought. At least that’s what Dr. Farhi believes.
“The finding of water in a large asteroid means the building blocks of habitable planets existed–and maybe still exist–in the GD 61 system, and likely also around a substantial number of similar parent stars. These water-rich building blocks, and the terrestrial planets they build, may in fact be common.”