(June 10, 2024)

Evidence of a long-ago collision involving the Earth was there in the form of specific radioactive isotopes deposited across the Earth and Moon. There were, however, skeptics.

But now researchers have tracked the sun’s path through the Milky Way back to a crash 2 to 3 million years ago with a dense interstellar cloud. The event was so violent it appears to have collapsed the sun’s protective bubble around the solar system and possibly even affected life on Earth.

(…)

“We don’t often discuss the impact of astrophysics on Earth because the astronomical timescales are very long, and the human species emerged on Earth just a few million years ago,” Loeb said. “But a few million years ago there was the potential for us to be passing through a very dense cloud. We didn’t work out the biological implications, but it’s clear that if you shrink the heliosphere to within the orbit of the Earth around the sun, we are not protected anymore. It could have significant implications for life on Earth.”