Artist's conception of the massive collision between Earth and a Mars-size object that likely created the moon about 4.5 billion years ago.

Gigantic collisions

In the last days of

These traumatic

"We can use

The mystery of

Gold, platinum,

But siderophiles are

"The abundance

One possibility is

Bottke and his

Modeling planet

To account for

Using numerical

"The

The results show

These big

This bombardment

Bottke and his

Other evidence

The results from the

For example, other

"The

A 1,000-mile-wide

Taken together, the

"We have a

Is this violence

The study paints a

"Because we can

If our solar system

In any event, Bottke

"If you can

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