Alien impacts gave Earth its gold

If you’re giving gold or platinum this Christmas, your present really will be out of this world. For new evidence reveals these precious metals were dumped on Earth in colossal cosmic collisions.

Artist's impression of planetary impact
Artist’s impression of planetary impact (NASA)

Scientists say our region of the solar system was bombarded by giant asteroids up to 2,000 miles wide around 4.5 billion years ago. We can still see the scars on the Moon today.

The massive impacts left the valuable metals such as gold and platinum in the Earth’s crust from where we are able to mine it today. Similar finds should also be awaiting us on the Moon and Mars.

US researchers argue that any metals like these that were originally in our planet would have been pulled down towards its central iron core. That would put them well out of reach and jewellers and commodity dealers would not have access to such precious assets.

The bombardment by mini-planets as big as Pluto happened tens of milions of years after a bigger impact caused material to break off the Earth and form the Moon.

The research is published this week in the journal Science by a team from the University of Maryland, the Southwest Research Institute, the Massachusetts Institute of Technology, and the Scripps Institution of Oceanography.

Professor Richard Walker of the University of Maryland said: “Our understanding of the formation of Earth and other planets with iron cores and silicate mantles suggests that iron-loving elements are pulled into the planet cores as they form.

“Thus, we should have an Earth that essentially has no gold or other iron-loving metal ores in its crust for us to mine.”

The team say their computer models of the cosmic missiles that caused the bombardment are supported by the observed sizes of asteroids today and of ancient impact scars on Mars. There have been claims that similar collisions have been observed around a star in the Seven Sisters cluster.

• Discover space for yourself and do fun science with a telescope. Here is Skymania’s advice on how to choose a telescope. We also have a guide to the different types of telescope available. Check out our monthly sky guide too!

©PAUL SUTHERLAND, Skymania.com

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Paul Sutherland

Paul Sutherland

I have been a professional journalist for nearly 40 years. I write regularly for science magazines including BBC Sky at Night magazine, BBC Focus, Astronomy Now and Popular Astronomy. I have also authored three books on astronomy and contributed to others.
Paul Sutherland

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Paul Sutherland

I have been a professional journalist for nearly 40 years. I write regularly for science magazines including BBC Sky at Night magazine, BBC Focus, Astronomy Now and Popular Astronomy. I have also authored three books on astronomy and contributed to others.

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