In the beginning;
Early life probably fell victim to massive space rocks
Planet-sterilizing asteroids struck Earth until around 4.3 billion years ago
by Thomas Sumner 8:09am, July 31, 2014
"Space rocks larger in diameter than Spain bombarded the early Earth, probably repeatedly eradicating emerging life. The last of these death rocks struck around 4.3 billion years ago, scientists estimate in the July 31 Nature, providing an upper limit to when life first took hold on Earth.
From Earth’s origin around 4.6 billion years ago until 3.8 billion years ago, the planet was such a hellish place that geologists call this eon the Hadean after Hades, the Greek god of the underworld. Debris left over from the solar system’s creation regularly slammed into Earth, boiling away the early ocean and coating the planet with molten rock.
But it was during this chaotic period that scientists think life arose on Earth."https://www.sciencenews.org/article/ear ... b-93287133
And in the end;
Siberian crater mystery may be solved
by Science News Staff 3:00pm, August 1, 2014
"Methane, not an alien spacecraft crash, is probably responsible for the 30-meter-wide crater that suddenly appeared in Siberia in mid-July.
While air normally contains just 0.000179 percent methane, air near the bottom of the crater was composed of 9.6 percent methane, Nature reports. Researchers suspect that rising summer temperatures in the region thawed permafrost in the ground. As the soil defrosted, methane gas trapped in the permafrost pooled underground before bursting to the surface and ripping a hole in the ground.
Scientists believe that as regional temperatures rise, these kinds of craters could become more common."https://www.sciencenews.org/blog/scienc ... b-93287133
Could it be that LIFE is self-eliminating? By the mechanism of enough methane turnover to turn a planet to Venus-like?