Forget the Eclipse, the ‘Largest’ Asteroid Ever Tracked by NASA Is About to Roar Past Earth

NASA’s Paul Chodas wants to make one thing perfectly clear: Planet Earth isn’t about to get obliterated by a giant killer asteroid.

Nevertheless, when the 2.7-mile-wide object known as Asteroid Florence roars past Earth at a blistering eight miles a second—its closest fly-by of our planet in over 600 years—on Sept. 1 at 2:40 p.m. ET, it’s still going to be a “remarkable” event.

“It’s the closest that an asteroid this large has ever come to the Earth,” says Chodas, manager of NASA’s Planetary Defense Coordination Office, located in Pasadena, California. “So it’s remarkable from that point of view. On the other hand, it’s passing by at a safe distance, roughly 18 times the distance between the Earth and the moon.”

That works out to about 4.4 million miles, something Chodas describes as “pretty far from a human perspective, but astronomically it’s a close approach, a remarkably close approach.”

But that’s good news for sky watchers—because of its proximity, the asteroid should be visible with the use of a typical backyard telescope, and Sky & Telescope magazine published charts to help locate the space rock as it passes through the constellations Aquarius, Capricorn, Delphinus, Cygnus and Vulpecula. The magazine says Florence will reach its peak brightness from late August 31 to early September 1, but will remain bright for a few days after. They say the best time to view the asteroid during this period is September 2 at around 8 p.m. EDT, as Florence crosses through the constellation Delphinus.

For those without a telescope on hand, you’re still in luck, as astrophysicist Gianluca Masi will be leading a free webcast of the flyby with the Virtual Telescope Project starting at 3:30 EDT on September 1 (you can watch it here).

Scientists like Chodas have calculated that the orbit of the rocky, mountain-sized Florence (named after Florence Nightingale, the founder of modern nursing) won’t pass any closer to Earth until after the year 2500.

And even then, the data doesn’t indicate that it’s going to hit our planet in the foreseeable future.

“We know its orbit really well and we’ve projected into the future and we know that it can’t approach much closer than this for at least a millennia,” Chodas explains. “So it’s safe to say that we are safe from a collision.”

Which is a good thing. Because any asteroid larger than one kilometer—or roughly 0.6 of a mile—that hits Earth has the potential to be “globally catastrophic” and could “kill off civilization” as we know it.

The asteroid that scientists believe led to the extinction of the dinosaurs has been calculated to have been six miles across, a little more than twice the size of Florence.

“Florence isn’t a hazard, but we are on the lookout for other ones that could pose a hazard to the Earth,” adds Chodas, whose team has identified roughly 940 asteroids larger than one kilometer in our cosmic neighborhood.

“Space is littered with this stuff. And our job is to search for the ones that could be hazardous.”