Astronomers have discovered three asteroids that had been “hiding” unseen in the sun’s glare. The space rocks are considered near-Earth objects—meaning their orbits take them within roughly 120 million miles of the sun.
The biggest of the three asteroids, named 2022 AP7, is nearly one mile wide—large enough to be called a “planet-killer.” And it has an orbit that might one day cross paths with Earth’s, according to a Monday statement from NOIRLab, which operates the telescope that spotted the asteroids.
But the discovery should not be cause for alarm, experts say. “There is an extremely low probability of an impact in the foreseeable future,” Tracy Becker, a planetary scientist at the Southwest Research Institute who did not contribute to the work, tells the New York Times’ Robin George Andrews.
Scientists say 2022 AP7 will stay away from Earth, for now. But the asteroid might not be harmless forever. “Way down the line, in the next few thousand years, it could turn into a problem for our descendants,” Alan Fitzsimmons, an astronomer at Queen’s University Belfast in Northern Ireland who did not contribute to the work, tells the Times.
In the event that the asteroid collides with our home planet at a far-future date, “it would be a mass extinction event like hasn’t been seen on Earth in millions of years,” Scott Sheppard, an astronomer at the Carnegie Institution for Science, says to CNN’s Ashley Strickland.
Sheppard and others detailed their discovery in September in The Astronomical Journal.
All in all, astronomers have found 27,000 near-Earth asteroids, per CNN. Of these, just under 1,500 have some (incredibly small) chance of colliding with Earth during the next 100 years, according to Gizmodo’s Isaac Schultz.
The near-Earth asteroids hold a minimal risk, but in case of a future threatening space rock, scientists are developing protective techniques. In September, NASA’s DART mission successfully shifted the orbit of a small, benign asteroid by bumping it with a spacecraft.
While astronomers have spotted thousands of near-Earth asteroids, they’ve only found about 25 that are inside Earth’s orbit—a task that is “incredibly difficult… with our current discovery telescopes,” Cristina Thomas, a planetary astronomer at Northern Arizona University who did not contribute to the research, tells the Times.
For one, the sun’s glare makes them hard to see. And astronomers hoping to find these objects have to look near the horizon, where the thickness of Earth’s atmosphere distorts the view, per NOIRLab. Plus, they only have two ten-minute windows to search the inner solar system for these objects each night.
To make their discovery, researchers used the Dark Energy Camera (DECam) on the Víctor M. Blanco 4-meter Telescope in Chile. “DECam can cover large areas of sky to depths not achievable on smaller telescopes, allowing us to go deeper, cover more sky and probe the inner solar system in ways never done before,” Sheppard says in the statement.
Neither of the two other asteroids spotted has an orbit that intersects with that of Earth, per NOIRLab.
One of these two is the closest known asteroid to the sun, and, like 2022 AP7, it's considered a “planet killer.” Though astronomers have already located most asteroids of this size, “we know some are still out there to find,” Fitzsimmons tells the Times.