A small asteroid just gave Earth and some satellites a very close pass

A piece of cosmic debris named 2021 GW4 briefly dove beneath the orbit of many of our largest satellites Monday.

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Eric Mack
2 min read

An artistic impression of a near earth asteroid.

Theodore R. Kareta

A small space rock about the size of a car or truck made a slightly intrusive but not very intimidating flyby on Monday.

Asteroid 2021 GW4 came within 12,324 miles (19,833 kilometers) of the surface of Earth at its closest point of approach Monday morning Pacific time, according to Harvard astronomer Jonathan McDowell.

That puts the asteroid well inside the ring where many large artificial satellites orbit Earth at an altitude of 22,236 miles (35,786 kilometers).

"Fortunately space is still rather empty at these altitudes," McDowell wrote on Twitter.

He estimated that the nearest functioning satellite to the asteroid's path was a military GPS satellite about 1,243 miles (2,000 kilometers) away.

NASA estimates the asteroid's diameter at between 11 and 25 feet (3.5 and 7.7 meters). That's small enough that the entire thing would likely burn up if it collided with our atmosphere.

2021 GW4 was originally spotted on April 8 by the Mt. Lemmon Survey in Arizona, another example of the improving ability of such surveys to spot even very small asteroids passing extremely close by. Often such space rocks are only discovered hours before their closest pass, or even when they are already in our planetary rear-view mirror.

So far in 2021, only two asteroids have come closer to the surface of our planet. But just like the vast majority of all the objects in our immediate cosmic vicinity, none ever posed a real threat.

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