Nov 12, 2020 - Science

The age of an asteroid

Miriam Kramer

A boulder seen on Bennu pictured in false color — A boulder on Bennu. Photo: UofA/JHU-APL/York University

The asteroid Bennu has been orbiting the Sun not far from Earth, for about 1.75 million years, according to a recent study.

The big picture: By combining the new findings with data from a sample of the asteroid, researchers hope to learn more about the chaotic early days of our solar system and to figure out how Earth eventually gave rise to life.

What they found: The scientists behind a study in the journal Nature used images from NASA's OSIRIS-REx mission to Bennu to count craters on the asteroid's surface in order to estimate how long it has been in the inner solar system.

Older objects have had more time for craters to accumulate and counting the features on planetary surfaces is a longstanding technique.
"The amazing data collected by OSIRIS-REx at asteroid Bennu have allowed us to not just find impact craters across its surface, but to actually find and study the craters on the surfaces of boulders," Kevin Walsh said in a statement.

What's next: OSIRIS-REx nabbed a sample of the space rock that will be returned to Earth in 2023 and will offer more clues about Bennu's — and Earth's — past.

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The age of an asteroid

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