Astronomers have discovered a captive asteroid shadowing Earth in its orbit.
The asteroid, known as 2020 XL5, is only the second of its type ever seen, shepherded by Earth’s gravity into an orbit that is locked in synchrony with our planet’s. It has not shared our orbit for long — a few centuries, probably. And it will not be there in the far future. Simulations indicate that 2020 XL5 will slip out of Earth’s grasp within 4,000 years and head into the wider solar system.
But its presence offers a tantalizing glimpse of what else might be out there in the local gravitational whirlpools. Some bits might date back to the beginning of the solar system — shades of the building blocks that coalesced into our planet.
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