Asteroid 2022 AE1 poses no danger to Earth

Diagram of solar system with white oval line for asteroid's elongated orbit.
The recalculated orbit of Asteroid 2022 AE1 shows it will safely pass by Earth on July 1-2, 2023. The sun is at the center, the blue ring represents Earth and the white ring represents asteroid 2022 AE1. Image via NASA/JPL.

Asteroid 2022 AE1 caused a bit of a stir following its discovery on January 6, 2022. Scientists at NASA’s Jet Propulsion Laboratory in Pasadena California temporarily placed it in level 1 on the Torino scale. The scale is intended to convey the seriousness of a given asteroid’s potential for collision with Earth. It goes from 0 to 10. A 10 on the Torino scale indicates a collision is certain, and the impacting object is large enough to precipitate a global disaster. All other known asteroids on the Torino scale are currently level 0. They pose no risk of impacting Earth. Why was 2022 AE1 placed at 1 on the Tonino scale?

A little while after 2022 AE1’s discovery, scientists moved it back down to level 0, only to move it back to level 1 when they realized it would have a close encounter in early July 2023. Then, on January 20, 2022, the asteroid 2022 AE1 entered the list of Removed Objects. Time to breathe a sigh of relief. But why? Why didn’t astronomers know all along?

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How big is it?

Asteroid 2022 AE1 is an Apollo-type asteroid. It has an estimated size of 230 feet (70 m) in diameter. It’s more than three times the size of the small asteroid that disintegrated over the skies of Chelyabinsk, Russia, on February 15, 2013. It’s about the same size as the space rock that caused the Tunguska event in 1908, also in Russia, which released enough energy to kill reindeer and flatten an estimated 80 million trees over an area of 830 square miles (2,150 square km). In 1908, witnesses reported seeing a fireball – a bluish light, nearly as bright as the sun – moving across the sky. A flash and a sound similar to artillery fire was said to follow it. A powerful shockwave broke windows hundreds of miles away and knocked people off their feet.

So asteroid 2022 AE1 is, apparently, plenty big enough to cause a “destructive event” on Earth. Why didn’t astronomers know for certain how dangerous it was? And why did it cause a stir?

Lowering, raising and lowering the risk

The fact is that asteroids are relativity small bodies in space. They are rocky or metallic objects, left over from the formation of our solar system some 4.5 billion years ago. As of January of last year, there were about 822,000 known asteroids. And more are being discovered all the time. Earthly astronomers are, of course, most interested in those asteroids whose orbits carry them near Earth. But – while astronomers do have solid knowledge on the large asteroids, those tens or hundreds of miles across – they just don’t know all the smaller asteroids yet.

Astronomers discovered Asteroid 2022 AE1 on January 6, 2022, using the 60-inch (1.52-meter) telescope at Mount Lemmon Observatory in Arizona. Initial calculations indicated a very small impact probability during its next flyby in July 2023. Of course, 2022 AE1 has been sweeping past us for perhaps bilions of years. For example, we know now it was closest to Earth about a week before its early January 2022 discovery. Closest approach of this asteroid to Earth had already occurred when they spotted it. It happened back on December 31, 2021, at a huge, safe distance of 6,174,814 miles (9,937,400 km). Telescopes didn’t spot it earlier because it approached Earth from the sun’s direction. Asteroids coming from the direction of the sun are hard to see.

But back to why it caused a stir. Astronomers tracked its orbit for just a few days in early January, before it was temporarily “lost” from observatory telescopes around January 12. A bright waxing moon was sweeping near it in the sky, temporarily hiding the asteroid in the lunar glare. Around that time, the asteroid garnered attention because it popped up on the Torino Scale. All other object on the scale are at level 0: no risk. 2022 AE1 was temporarily at level 1. So it was noticeable! And temporarily hidden by the moon.

But the projected risk from 2022 AE1 was never very high. Initial calculations indicated the space rock had 1 in 1,700 odds of impact. That equals a 99.94% probability that it will safely pass and miss planet Earth. New estimates placed its chances of striking Earth even lower. New observations on January 20, 2022, put Asteroid 2022 AE1 at a 1 in 71,000 odds of impact. Or, there’s now a 99.9986% chance the asteroid will miss Earth during its next pass in 2023.

To track an asteroid’s orbit with any certainty, astronomers need more than a few days of observations. In fact, scientists initially calculated 2022 AE1’s next flyby to occur on July 4, 2023. But later calculations showed it instead passes safely on July 2, 2023, at 00:05 UTC.

As the moon moved away, and astronomers were able to “recover” asteroid 2022 AE1, they learned more about it. The new observations also show the space rock has a speed of 39,504 miles per hour (63,576 km/h or 17.66 km/s) relative to Earth. It completes an orbit around the sun every 652 days (1.79 years).

On July 1-2, 2023, the 230-foot space rock will return, passing at a nominal distance of 4,192,066 miles (6,746,476 km) from Earth.

Asteroid 2022 AE1 won’t hit Earth

So, no, an asteroid will not cause fireworks on the 4th of July next year, as some media initially suggested.

However, as is common with new discoveries, additional observations allowed astronomers to make more exact calculations of the space rock’s orbit.

Yes, there is still some uncertainty. But, even so, the closest this space rock might come next year is at a minimum distance of 356,710 miles (574,069 km) from Earth’s surface (farther than the moon).

There is no danger.

Bottom line: A newly discovered asteroid, 2022 AE1, was temporarily at level 1 on the Torino scale of impact hazards. It is now removed from the list as revisions to its orbit show it poses no danger to Earth.

January 25, 2022

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