14 DAY TRIAL // Most people only think of comets as enders of worlds, but some scientists are making a strong case that the space objects are more likely cosmic arks of life, taking life-precursor molecules through space in all directions.
Some of these objects may have done this for our planet as well, say investigators. In addition to causing several extinction events, comets may have also seeded the planet with all the elements necessary to support the development of basic life forms.
One of the most common and important molecules that these objects may have brought here is water, a chemical that can be found in abundance both on Earth and on comets.
This explanation helps researchers make sens of why so much of the stuff exists on this planet, whereas other bodies in the solar system are completely barren.
The idea makes a lot more sense when considering how Earth looked like some 4.6 billion years ago, when it formed. It was a ball of hot, molten lava at first, which then solidified over a period of 50 to 100 million years old.
The even left behind an empty planet, that is unlikely to have had any water. So the question that astronomers and planetary scientists have to answer is “Where did all the water come from?”
“As such, for a long time, people thought water was delivered sometime after the Earth formed and cooled down a bit,” says scientist David Jewitt.
“So people looked around at what kinds of things loaded with water might hit Earth, and comets were the obvious answer,” adds the expert, who is an astronomer at the University of California in Los Angeles (UCLA).
Comets are the most handy explanation, given that they are, in essence, large chunks of space ice around a rocky core.
“My guess is that Earth's oceans were formed as a contribution of all three – comets, the asteroid belt, and the primordial material that went up to make the Earth,” Jewitt goes on to say.
“It's just a question of finding out which was the biggest source,” the expert adds, quoted by LiveScience.
Also, while it may seem counter-intuitive to some, our planet itself may have trapped some water in its rocks when it formed. The liquid was then released to the surface, where it began accumulating.
“It's hard for most people to see how hot rock can trap much water, but the argument there is that, overall, Earth is not all that wet,” Jewitt says.
“The mass of the oceans is only a few hundredths of 1 percent of Earth's total mass, which is pretty dry,” he concludes.