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.
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
