Star trails circle the Celestial South Pole
Star trails circle the Celestial South Pole near a radioastronomy antenna at the Asociación Argentina Amigos de la Astronomía facilities. Flickr image by Guille, published under Creative Commons Licence

Aug. 3, 2022

Building-sized asteroid flyby nothing to be concerned about

UCalgary expert says newly discovered space rock has unique characteristics, but was unlikely to threaten the Earth

While many of us were having supper on Aug. 3, an asteroid roughly the size of the Empire State Building hurtled past Earth.

Thankfully, even as astronomers kept a keen eye on the big rock, there was no need to channel our inner Bruce Willis in Armageddon, Dr. Jeroen Stil, PhD, an associate professor in the Department of Physics and Astronomy at the University of Calgary, said prior to the 6 p.m. flyby.

“This one is a comfortable miss, he said. Astronomers predicted it would miss the Earth by more than 5 million kilometres.

The space rock, dubbed 2022 OE2, was only discovered on July 26. Stil noted it is fairly big for a recently discovered near-Earth object (NEO).

Unique characteristics

He said 2022 OE2, which is estimated by NASA to be up to 380 metres across, is not much smaller than some of the big NEOs that scientists thought had all been discovered. “This is a reminder that there are things around out there that we don’t know of,” said Stil.

Another unique characteristic of this asteroid is its orbit. According to Stil, the asteroid’s orbit is more stretched than a typical orbit, going almost as far out as the orbit of Jupiter, passing the Earth and getting closer to the sun, to within Mercury’s orbit.

Most asteroids in the solar system are located within the asteroid belt, between the orbits of Mars and Jupiter, and they stay within the belt. However, there are about 20,000 asteroids that come near to Earth.

Stil said 2022 OE2 is a standout because it crosses the Earth’s orbit, along with the orbits of Mars, Venus and Mercury. “When I look at the orbit in detail, it stays below the Earth’s orbit,” he said. “I don’t think this is a particularly hazardous one.”

Things get dicey when an asteroid intersects with the plane of the Earth’s orbit, making the potential for impact much higher.

Visible from South Pole 

Unfortunately, for any stargazers in Calgary hoping to see this flyby, the asteroid passed by underneath the Earth, meaning it was only visible from the South Pole, and even then, only with some very powerful equipment.

“It would have to be a really strong telescope, as this thing is several times fainter than the planet Pluto in the sky,” said Stil.

Though it presented very little risk to the planet, 2022 OE2 garnered a fair amount of media attention, and Stil said it might be the game of chance that the rock presented that made it so fascinating.

“If it had come straight for us, we would have had a space rock of a few hundred metres across come down with a few days notice,” he said.

Asteroids have had a starring role in more than a few Hollywood disaster films, so the idea of a cataclysmic impact has long captured the public consciousness.

In real life, the Earth has not been 100-per cent lucky when it comes to avoiding space objects. Stil said the Earth is hit by meteoroids quite often, and there have been a few noticeable impacts in the past century.

All eyes on space rock

As more cameras and satellites are set up to scan the Earth, Stil said we are becoming more aware of falling space rocks.

There are asteroids that pass much closer to the Earth, with Stil noting there was one just last month that passed well within the distance to the moon, and about 30 times closer than 2022 OE2's approach.

For Stil, the latest asteroid shows there are NEOs out there that have yet to be found and could present future hazards.

“It gives you pause every time an object like that comes out of nowhere that we didn’t know about and passes close to Earth,” he said.