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From a distance, everything in our solar system appears to be in its place.

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However, if you take a closer look, sometimes you can find asteroids, like Bennu,

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leaving their home in the inner asteroid belt and passing very close to Earth.

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Most other asteroids tend to stay grouped together in a few regions of our solar system, yet some still end up in our backyard.

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So once these asteroids get close, what makes the difference between a near-miss, and a potential hit?

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NASA's OSIRIS-REx mission will help better answer this question when it visits Bennu,

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but scientists think that a force called the Yarkovsky effect might be an important part of the answer.

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So how does this effect work? Well, like Earth, most asteroids rotate slowly as they move through space.

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During the day, the surface of the asteroid is illuminated by the Sun, so it absorbs heat and grows warmer.

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During the night, however, the surface cools down, emitting the heat it absorbed as radiation.

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This radiation exerts a force on the asteroid, acting as a sort of mini-thruster that can slowly change the asteroid's direction over time.

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On larger asteroids this doesn't amount to much, but on small ones it can make a pretty large change over time.

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Because the surface emits the most heat radiation at the end of the day,

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the direction the asteroid rotates can ultimately determine what happens in the long run.

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Other factors, such as composition, asteroid shape, and surface features, can modify the magnitude and direction of the Yarkovsky thrust.

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By studying the Yarkovsky effect on Bennu with the OSIRIS-REx spacecraft,

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NASA scientists hope to better predict how an asteroid might move through the solar system,

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and whether it poses any danger to us here on Earth.

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So the next time an asteroid starts gradually moving into our neighborhood, we'll have a better idea of exactly where it will end up.

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