Sentences with phrase «here by comets»

First, planetary scientists suspect that cyanide was abundant on early Earth, deposited here by comets or created in the atmosphere by ultraviolet light or by lightning (once the atmosphere became oxygen rich, 2.5 billion years ago, the process would have stopped).

Not exact matches

They are «stardust» and were brought here (and to other planets as well) by comets, meteors, and other debris.

Those pictures, some of which are sharp enough to spot features 10 centimeters across, were taken by the European Space Agency's Rosetta probe, which has been orbiting the comet (seen here in July from a distance of about 160 kilometers) for more than a year now.

Chunks of the moon and Mars (blasted free by other impacts on those bodies) and comets can also make their way here.

My point here is we are entering a current of thinking, developed by a few scientists all over the world, reconsidering the time of humans in terms of multiple comet impacts, not all of them yet known.