Avi Loeb

of the age of the Milky Way galaxy.

It's nothing.

Yeah, but it's not really documented in written form.

Right.

It's picked up, perhaps, though.

But you are correct that...

Our knowledge of what happened on Earth is really limited because the human species existed for a few million years, and we have documentation at the level of 10,000 years.

If you go back to that, it would be 11,000.

Not a lot.

Not much more.

No, Mars is a less massive planet than the Earth.

and therefore it has less gravitational grip on its atmosphere.

And as to why the atmosphere was lost, there are various ideas.

You know, it may have to do with an eruption on the sun that removed it, or the magnetic field, the lack of a strong enough magnetic field to retain the atmosphere.

We don't know for sure, but we know it happened about two to two and a half billion years ago, at the middle of its life.

I actually did a calculation.

The biggest risk for anything on the surface is all these impacts by asteroids.

That's right.

That's right.

And I calculated the amount of energy over a few billion years that was deposited on the surface of Mars is equivalent to hundreds of Hiroshima...