An Asteroid Will Buzz by Earth on Halloween

Don’t worry—it won’t interrupt your Halloween plans

halloween asteroid
SEBASTIAN KAULITZKI/Science Photo Library/Corbis

This Halloween, Earth is getting an unexpected visitor. A newly-discovered asteroid called 2015 TB145 will skim past our planet just outside of the moon’s orbit, about 300,000 miles away.

First things first: Don’t panic.

While 2015 TB145 is the largest-known asteroid scheduled to buzz by Earth until 2027, NASA astronomer Davide Farnocchia says there’s “absolutely no chance” that it will collide with our planet, Loren Grush reports for The Verge. It’s not even the closest that an asteroid of this size has flown past Earth in recent years—that honor goes to asteroid 2005 YU55, which flew by at a distance of 0.85 lunar distances in 2011.

While there’s no need to worry about an apocalyptic collision, 2015 TB145’s appearance is surprising, as astronomers didn’t spot it until October 10, the same day that another asteroid passed by about 15 million miles away from Earth, Todd Leopold reports for CNN. There are a few reasons why 2015 TB145 escaped detection for so long, namely because its orbit is longer and at a different angle than most other asteroids in the solar system.

As Phil Plait writes for Slate’s Bad Astronomer:

It’s...on a very elongated orbit that takes it closer in to the Sun than Mercury, and about half the distance out to Jupiter. The orbit is also highly tilted; it’ll come at us from the south, cross Earth’s orbit, move up to the north for a while, and then back down again…

This unusual orbit is why it was only discovered on Oct. 10! Most asteroids stick near the plane of Earth’s orbit. Worse, it’s coming from the south, and there are fewer observatories in the Southern Hemisphere scanning the skies to look for passing rocks.

The astroid is also a bit unusual in its size and speed. 2015 TB145 is about 1,640 feet in diameter, which is pretty big for asteroids zipping by Earth, according to a report by NASA’s Jet Propulsion Laboratory. The asteroid is also flying at unusually high speeds of almost 22 miles per second compared to the average asteroid velocity of about six miles per second, Grush reports.

Even so, one of the reasons that NASA didn’t detect 2015 TB154 until now is because it’s too small to worry about. NASA is mostly concerned with asteroids that are more than 3,200 feet wide, which could possibly wipe us out if they were to collide with the Earth, As Grosh reports.

The asteroid’s visit might have been a surprise, but its close orbit presents astronomers with a rare and exciting chance to observe it up close. This is “a truly outstanding scientific opportunity to study the physical properties of this object,” according to NASA’s report.

While its angle of approach will make 2015 TB154 hard to see with an optical telescope, you can watch it live via the Virtual Telescope Project.

If 2015 TB154 were to hit the Earth (which it won’t), it probably would be pretty destructive. After all, the meteorite that exploded above Chelyabinsk, Russia in 2013 was only about 66 feet wide. Luckily, NASA believes it has mapped out about 90 percent of asteroids of that size in our solar system, none of which pose a threat to the Earth. So go forth and trick or treat. No need to fear the asteroid.

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