The 1.5 kilometer (0.9 mi) wide asteroid, named 2022 AP7, was discovered in an area notorious for making it difficult to detect objects due to the glare of the sun.
It takes 2022 AP7 five years to revolve around the sun under its current
orbit, which remains at its closest point to Earth at several million
The risk to this is minimal, Sheppard said, but in the event of a collision, an asteroid of this size "would have a devastating effect on life as we know it." He explained that the dust released into the air would have a significant cooling effect, leading to "an extinction event like we haven't seen on Earth in millions of years."
"2022 AP7 crosses Earth's orbit, making it a potentially dangerous
asteroid, but it does not currently or at any time in the future have a
path to collide with Earth," astronomer Scott Sheppard said. Carnegie
Institution for Science.
The potential threat comes from the fact that like any object orbiting it, its trajectory will be slowly modified by the myriad gravitational forces, particularly by the planets. So the outlook is difficult in the long term.
The newly discovered asteroid is "the largest potentially hazardous object on Earth discovered in the past eight years," NOIRLab, a US-funded research group that operates several observatories, said.
His team's findings were published in The Astronomical Journal. The other two asteroids pose no danger to Earth, but one is the closest asteroid to the Sun ever found.
About 30,000 asteroids of all sizes - including more than 850 larger than one kilometer - have been classified near Earth, earning them the designation "Near-Earth Objects" (NEOs).
None of them threaten the Earth for the next 100 years. According to Sheppard, "there are likely 20 to 50 NEOs to be found," but most are in orbits that put them in the glare of the sun.
In preparation for the future discovery of a more threatening object, NASA conducted a test mission in late September in which a spacecraft collided with an asteroid, proving that it is possible to change its course.