What Would Happen if 'Planet Killer' Asteroid 2022 AP7 Hit Earth?

Scientists have discovered a huge asteroid that occasionally crosses Earth's orbit around the sun, giving rise to the possibility that it could one day collide with our planet in the far distant future.

The space rock, called 2022 AP7, is one of three that were recently found as part of an asteroid survey being carried out by scientists using the Dark Energy Camera with the Víctor M. Blanco 4-meter telescope in Chile.

The other two, called 2021 LJ4 and 2021 PH27, occur completely inside Earth's orbit closer to the sun, so do not pose a risk to our planet. Until their discovery, all three space rocks had been hidden by the sun's glare. The study was published in The Astronomical Journal on September 29.

Asteroid 2022 AP7 is large with an estimated diameter of between 1 kilometer and 2.3 kilometers (0.6 to 1.4 miles). Scott Sheppard, staff scientist at the Earth & Planets Laboratory at the Carnegie Institution for Science and lead author of a study outlining the discovery of the asteroid, told The Guardian newspaper: "Any asteroid over 1 kilometer in size is considered a planet killer."

Asteroid hitting Earth
A stock illustration depicts a large asteroid burning up in Earth's atmosphere shortly before impact. A "planet killer"-sized asteroid at least one kilometer wide might cause an extinction-level event but not necessarily destroy the Earth. RomoloTavani/Getty

For now, 2022 AP7 is nothing to worry about. It only crosses Earth's orbit when it is on the other side of the sun, and takes around five years to make a full orbit. However, it is possible that the asteroid could become more of a risk in centuries' time as the point at which it crosses Earth's orbit becomes closer to our planet.

In the event of an impact, 2022 AP7 would have a devastating effect on life on Earth, potentially sparking an extinction-level event the likes of which has not been seen for millions of years with enormous amounts of dust and pollutants being released into the atmosphere.

However, would it be a "planet killer" as its name implies? Not really, according to the Earth Impact Effects Program asteroid impact model.

Using a theoretical asteroid with the upper estimated diameter of 2022 AP7 and assuming a typical impact speed of 17 kilometers per second with a typical 45-degree impact angle, and assuming the asteroid is made out of dense rock, the free online model shows that immediate local affects would be devastating.

Anyone within 100 kilometers of the impact would find that their clothes would set alight, as would nearby wood and vegetation. Around five minutes later a huge blast of air would arrive, capable of toppling multi-story buildings.

About 1,000 kilometers away the effects would be much less severe. A shockwave may cause glass windows to shatter and seismic effects would be noticeable, but there would be no thermal effects according to the Earth Impact Effects Program model.

The model also states that Earth as whole would not be strongly disturbed by the impact and would lose negligible mass. In addition, there would not be any noticeable changes to Earth's tilt or its orbit.

In other words, while such an impact would be harmful to civilization and many forms of life, Earth itself would not be destroyed. In order for that to happen, such an asteroid would need to be far bigger.

"2022 AP7 is one of the mile-wide scary ones, albeit not a planet killer," Brad Gibson, director of the E.A. Milne Centre for Astrophysics at the University of Hull in the U.K., told Newsweek. "We can look back 65 million years ago and the impact that [the Chicxulub impactor] asteroid/comet had on Earth. That one was around 10 miles wide and did manage to wipe out the dinosaurs and something like 80 percent of the species on Earth at the time. Truly devastating, but even that 10-mile-wide chunk of rock/ice was not enough to 'destroy' Earth and/or 100 percent of its life.

"It's a 'fun'—for lack of a better phrase—exercise to speculate as to what would be needed to wipe out all life and make it inhospitable for millions of years. For typical densities and impact velocities, the best guess right now is something between 50 and 100 miles in diameter would do the trick."

Mark Burchell, professor of space science at the University of Kent in the U.K., told Newsweek there are multiple answers to how big an asteroid would need to be to destroy Earth. On the one hand, it is theorized that our planet was once hit by a space object so large that the scattered debris formed the moon.

Burchell added: "And then there is how bad is an impact such that it kills all life, including bacteria in the rocks below the surface? This is probably an impact by a 50-kilometer-wide (31-mile) rock hitting us at typical speeds. But this will be at a rate of impact of much less than 1 in a billion years.

"Next on the list is an impact that wipes out higher lifeforms. By now we are talking about something that leaves a large crater. This impactor, like the dinosaur killer, was probably 10 to 15 kilometers (6 to 9 miles) in diameter. Say every 100 million years.

"After that is an impact that causes global disruption and ends civilization. A three- to five- kilometer (1.8 to 3.1 mile) diameter object would do that. Once every million years perhaps."

Uncommon Knowledge

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