Astronomers say they have discovered the largest planet killer-sized asteroid in eight years, and that the huge space rock will cross Earth’s orbit.
The asteroid, named 2022 AP7, was reported by researchers looking for space rocks within the orbits of Earth and Venus.
Writing in the Astronomical Journal, lead study author Scott Sheppard and colleagues at the Carnegie Institution for Science in Washington say they have found three “rather large” asteroids, one of which – 2022 AP7 – crosses the Earth’s orbit, making it a potentially hazardous asteroid (PHA).
With a diameter of about 1.1km to 2.3km, the team say 2022 AP7 is the largest PHA discovered since 2014 and probably in the top 5% of the largest ever found.
“Any asteroid over 1km in size is considered a planet killer,” said Sheppard, adding that should such an object strike Earth, the impact would be devastating to life as we know it, with dust and pollutants kicked up into the atmosphere, where they would linger for years.
“The Earth’s surface would likely cool significantly from sunlight not getting to the planet. It would be a mass extinction event like hasn’t been seen on Earth in millions of years,” he said.
While the finding of 2022 AP7 may bring to mind visions of the asteroid Armageddon depicted in the film Don’t Look Up, the study also offers reassurance.
“It has no chance to hit the Earth, currently,” said Sheppard, noting that at present 2022 AP7 crosses the Earth’s orbit when the Earth is on the other side of the sun.
Sheppard added that slowly, over time, the asteroid will start to cross Earth’s orbit closer to where our planet is. But, he said, “this will be centuries into the future and we do not know the orbit of 2022 AP7 precise enough to say much about its dangers centuries from now.”
Sheppard said the team expect to find “a few more” planet-killer near-earth objects 1km in size or larger in the next year or two through their survey work, which uses the Blanco four-metre telescope in Chile.
Jay Tate, the director of the National Near Earth Objects Information Centre in mid Wales, told the Guardian he was not losing sleep over 2022 AP7, adding that the Earth was actually a very small target. “At the moment, anyway, the impact probability is fairly low. I wouldn’t say negligible, but fairly low.”
In September, Nasa launched its Dart mission, ploughing a spacecraft into an asteroid in an attempt to deflect the latter from its orbit. The mission was an attempt to test technology that could eventually be used to tackle space rocks that pose a threat to Earth. Last month, researchers confirmed Dart had been a success.
Tate said an approach like Dart might not be suitable for 2022 AP7, given the size of the asteroid, but there were other possible methods.
“Having said that, we’ve got bucketloads of time,” he said, adding it might be possible to use multiple Dart-like impacts to shift the asteroid’s path a little at a time.
