How Sunlight Pushes Asteroids

  • Released Wednesday, July 29, 2015
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Rotating asteroids have a tough time sticking to their orbits. Their surfaces heat up during the day and cool down at night, giving off radiation that can act as a sort of mini-thruster. This force, called the Yarkovsky effect, can cause rotating asteroids to drift widely over time, making it hard for scientists to predict their long-term risk to Earth.

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Near-Earth asteroids like Bennu pose a potential danger to our planet, so it's important to predict their orbits with great accuracy. Unfortunately, a phenomenon called the Yarkovsky effect can make these predictions difficult over long time periods. How does this effect work?

When sunlight strikes a rotating asteroid, the dayside heats up; as the asteroid turns, the night side cools and releases the heat, exerting a small thrust that can change the asteroid's direction over time. In order to learn more about this process on asteroid Bennu, NASA is sending a spacecraft called OSIRIS-REx to make detailed observations of Bennu's shape, brightness, and surface features. These factors are thought to influence the Yarkovsky effect, and understanding how will enable scientists to better predict the orbit of Bennu and other near-Earth asteroids.

ANIMATION - Sunlight alters the orbit of a rotating asteroid via the Yarkovsky effect.

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NASA's Goddard Space Flight Center

This page was originally published on Wednesday, July 29, 2015.
This page was last updated on Wednesday, May 3, 2023 at 1:49 PM EDT.

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