Tiny asteroid sets record for closest fly-by of Earth

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Astronomers using the robotic Zwicky Transient Facility (ZTF) at the Palomar Observatory in California on August 16 spotted a tiny asteroid just after it had zipped past the Earth at a distance of only 1,830 miles, the closest any asteroid has ever been seen to do so without hitting the ground.

Asteroid 2020 QG is about 10 to 20 feet (3 to 6 meters) across, or roughly the size of an SUV, so it was not big enough to do any damage even if it had been pointed at Earth; instead, it would have burned up in our planet’s atmosphere.

“The asteroid flew close enough to Earth that Earth’s gravity significantly changed its orbit,” says ZTF co-investigator Tom Prince, the Ira S. Bowen Professor of Physics at Caltech and a senior research scientist at JPL, which Caltech manages for NASA. Asteroids of this size that fly roughly as close to Earth as 2020 QG do occur about once a year or less, but many of them are never detected.

The ability to spot these things is continuing to improve, though it does not appear they have yet obtained enough information to predict 2020 QG’s full orbit, or when or if it will return.


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  • sippin_bourbon

    “There is nothing more exhilarating than to be shot at with no result.”
    ― Winston Churchill

  • Chris

    Boy does that thing look like a piece of pipe or other long rectangle.

  • Max

    The robotic camera took what appears to be 10 or more pictures of that section of sky to place on top of each other for a better resolution. A fast moving object will leave a streak. As it says in the article;

    “ZTF, which is funded by the National Science Foundation (NSF) and other collaborators, scans the entire northern sky every three nights in search of supernovas, erupting stars, and other objects that otherwise change or move in the sky. As part of a NASA-funded program, ZTF team members search for near-Earth asteroids. When these space rocks speed across the sky, they leave streaks in the ZTF images. Each night, machine-learning programs automatically sort through about 100,000 images in search of these streaks, and then narrow down the best asteroid candidates to be followed up by humans. This results in about 1,000 images that team members and students sort through by eye every day.”

  • Chris: What you are looking at is a smeared streak caused by the asteroid’s motion. This isn’t its shape. Note the stars are points. The telescope was tracking the stars, so that anything like an asteroid would be streaked because it was moving.

  • Whoops. I should have read all the comments before answering Chris’s comment. Max explained far better.

  • Chris

    Thanks to both – I should have looked closer

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