An asteroid twice as close as most satellites slips by Earth

First spotted Monday, a space rock just hours later gave our planet one of the closest buzzes ever and then kept on going.

An asteroid the size of a car made one of the closest passes to Earth ever seen, before rambling on back into space Tuesday.

Asteroid 2017 GM was discovered late Monday by the Mount Lemmon Observatory in Arizona and then made its closest pass a few hours later at a distance of around 10,000 miles (16,000 kilometers or 0.04 of the distance to the moon). For reference, most of our communications satellites orbit at an altitude of more than 20,000 miles.

"It is among the 10 known asteroids making the closest approach ever," Italian astrophysicist Gianluca Masi wrote in a blog post Tuesday. Masi co-founded the Virtual Telescope Project, which helped to determine the asteroid's orbit.


Asteroid 2017 GM spotted in a 30-second exposure from Tenagra Observatories in Arizona.

Gianluca Masi / Michael Schwartz

In fact, a review of the International Astronomical Union's huge chronology of asteroid passes (PDF) puts asteroid 2017 GM down as the fifth-closest observed pass of all time and the nearest shave since February 2016. We're expecting an asteroid to come even closer when asteroid 2012 TC4, which is five times larger than 2017 GM, flies by at just under 9,000 miles (14,400 km) on Oct. 12.

Of course, spotting nearby asteroids depends on the technology available to see them. We've only been able to capture these smaller space rocks whizzing by between the distance of the moon and us for the past couple of decades.

It sure seems like the more we watch, the more we see: 2017 GM whizzed by shortly after I finished writing about the two other asteroids observed roughly between the Earth and the distance to the moon this week.

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