Largest Asteroid Flyby Of 2021 Is Happening This Weekend

Artist impression of an asteroid in space. Image credit: Nazarii_Neshcherenskyi/

Asteroid 2001 FO32 is one large space rock. It was discovered 20 years ago and it occasionally comes close to our planet. On Sunday, March 21, this is happening again, with the asteroid passing by Earth at the extremely safe distance of 2 million kilometers (1.25 million miles) from Earth. This will be the largest asteroid flyby of 2021.

It is estimated that 2001 FO32 is between 440 and 680 meters (1,300 to 2,230 feet). This flyby is the closest one this object will have with our planet, so scientists are planning to learn about this rock when it's nice and close to us.

“We know the orbital path of 2001 FO32 around the Sun very accurately since it was discovered 20 years ago and has been tracked ever since,” Paul Chodas, director of the Center for Near Earth Object Studies, said in a statement. “There is no chance the asteroid will get any closer to Earth than 1.25 million miles.”

Two main types of investigations will be conducted to better understand Asteroid 2001 FO32. Radar observations will provide a better understanding of the shape and size of the asteroid. This will be conducted by the Deep Space Network, whose radio dishes are located in California, Spain, and Australia. It will hopefully constrain its dimensions, work out a rotation rate, and maybe even highlight some surface features or possibly small satellites.

“Observations dating back 20 years revealed that about 15% of near-Earth asteroids comparable in size to 2001 FO32 have a small moon,” added Lance Benner, principal scientist at JPL. “Currently little is known about this object, so the very close encounter provides an outstanding opportunity to learn a great deal about this asteroid.”

Path of 2001 FO32
This image shows the elongated and inclined orbit of 2001 FO32 and the inner planets (white ellipse). ImageCredit: NASA/JPL-Caltech

The second investigation will use NASA’s Infrared Telescope Facility (IRTF) to study the infrared properties of the asteroid. Light from the Sun is partially absorbed and partially reflected by the small celestial body. By study this reflected light, scientists can estimate what the asteroid is made of.

“We’re trying to do geology with a telescope,” explained Vishnu Reddy, associate professor at the University of Arizona’s Lunar and Planetary Laboratory in Tucson. “We’re going to use the IRTF to get the infrared spectrum to see its chemical makeup. Once we know that, we can make comparisons with meteorites on Earth to find out what minerals 2001 FO32 contains.”

The asteroid is too faint to be visible with your eyes alone, but if you have a small telescope you might be able to catch it, especially if you’re in the Southern hemisphere. 2001 FO32 next close passage will be in 2052 where it will be slightly further away than this time around.

While near-Earth objects are a risk, over 95 percent of all those larger than 2001 FO32 have been discovered and none of them pose a risk for Earth over the next century.


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