Space

Astronomers spot closest Earth-buzzing asteroid ever recorded

Astronomers spot closest Earth...
Asteroid 2020 QG, appearing as a streak in the sky in this image from the Zwicky Transient Facility telescope
Asteroid 2020 QG, appearing as a streak in the sky in this image from the Zwicky Transient Facility telescope
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Asteroid 2020 QG's trajectory is highlighted in green. The grey circle is the Moon's orbit. The yellow arrow points towards the Sun, while the blue arrow indicates the direction of Earth's movement
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Asteroid 2020 QG's trajectory is highlighted in green. The grey circle is the Moon's orbit. The yellow arrow points towards the Sun, while the blue arrow indicates the direction of Earth's movement
Asteroid 2020 QG, appearing as a streak in the sky in this image from the Zwicky Transient Facility telescope
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Asteroid 2020 QG, appearing as a streak in the sky in this image from the Zwicky Transient Facility telescope
An animation of asteroid 2020 QG's Earth-buzzing trajectory
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An animation of asteroid 2020 QG's Earth-buzzing trajectory
View gallery - 3 images

Astronomers have identified an asteroid that’s just made the closest pass to Earth ever recorded – and it was only spotted after it had passed. The object skimmed Earth’s atmosphere over the weekend, close enough to have its orbit changed by the planet's gravity.

On August 16, an asteroid designated 2020 QG whizzed past our planet at a distance of only 2,950 km (1,830 mi) above the surface. That’s well within the altitude of many satellites, and almost twice as close as the previous record-holder, an asteroid called 2011 CQ1. Of course, this record is about the closest pass to Earth, and doesn’t include objects that have impacted the planet.

That said, even if it had hit, asteroid 2020 QG wouldn’t have caused any damage. It measures about 3 to 6 m (10 to 20 ft) wide, meaning it would have just burned up in the atmosphere. Still, it is a little concerning that astronomers only noticed it hours after the fact, and highlights how important it is for telescopes to keep watching the skies for any bigger rocks that might be on a collision course.

An animation of asteroid 2020 QG's Earth-buzzing trajectory
An animation of asteroid 2020 QG's Earth-buzzing trajectory

Asteroid 2020 QG was discovered by the Zwicky Transient Facility (ZTF), which specializes in identifying transient events like supernovae or moving objects like asteroids. The latter appear as streaks as they zip past at high speeds. The telescope scans the whole Northern Hemisphere sky every three nights, creating about 100,000 images. These are then sorted by machine learning algorithms before the most promising candidates are passed down to human observers for follow-up.

"A lot of the streaks are satellites, but we can quickly go through the best images by eye to find the actual asteroids," says Bryce Bolin, a member of the ZTF team. "This latest find really demonstrates that ZTF can be used to locate objects very close to Earth that are on potentially impacting trajectories."

The team reported the discovery to the International Astronomical Union (IAU) Minor Planet Center, which will help astronomers all over the world to track 2020 QG and learn more about it.

Source: Caltech

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6 comments
Brian M
"That’s well within the altitude of many satellites"
Wonder what the affect of a collision with a satellite would be - A cascade of other satellite failures as the debris from the collision spread out and then the debris from those collisions take out even more satellites in a chain reaction or a simple vaporization of the satellite?

Do we need a better early warning system for smaller asteroids and a way, if possible, of diverting incoming rocks of this size.
Bob809
Brian M August 19, 2020 03:48 AM --- Nah, why bother spending that money on something that might never happen... All the idiot nay-sayers will have satellite egg on their collective faces (and hopefully lose their jobs) when it does happen.
martinwinlow
@ Brian M - It would be a lot easier to alter the satellite's path... given that they are helpfully equipped with radios and thrusters!
Eddy
So what will it hit next time round now it's orbit has been changed by our gravity.
toni24
"Closest approach"???
I seem to recall an old home movie of an asteroid that actually skimmed and bounced off the Earth's atmosphere around 1972 which was much larger
drBill
Perhaps it's just being picky, but "This latest find really demonstrates that ZTF can be used to locate objects very close to Earth that are on potentially impacting trajectories." is a recording process after the object has passed. The streak was the result of the heating of the atmosphere, and has no predictive value.