Mile-wide asteroid found hiding in the sun’s glare
On a beautiful spring day 66 million years ago, a killer asteroid came from outer space and crushed the dinosaurs to extinction. They couldn’t have seen it coming or done anything about it, but maybe we can. If the events of Asteroid vs Earth (now streaming on Peacock!) ever come true and we face another killer space rock, our only hope will be to see it with enough advanced warning to knock it off course (as tested by NASA’s Recent Dart Mission).
That’s a relatively simple attempt — in principle, if not in practice — for things that come from outside the solar system. All we have to do is point our telescopes at the night sky and look. Objects large enough to actually threaten Earth aren’t that hard to find, but things can get complicated if we look at the interior of the solar system. That’s because looking at things closer means you’re looking at the sun. It’s the astronomical equivalent of trying to see someone’s face while they’re in the spotlight, and you don’t know exactly where they are or if there is a person at all.
That’s why astronomers have so far identified only about 25 asteroids with orbits completely within Earth’s orbit. That may be due in part to their relative rarity, compared to objects farther away than us, but it’s certainly determined by how difficult it is to see into the sun’s glare. To make matters worse, a lot telescopes are not designed to face or face the sun. Scientists needed a specialized instrument to look at the right parts of the sky, and they found it in Chile.
There, an international team of scientists used the Cerro Tololo Inter-American Observatory’s Dark Energy Camera to scan the sky at dusk. Every day there were only two 10-minute windows, on the border between day and night, in which they could make observations. Despite the laborious and uncooperative conditions of the work, researchers managed to identify three new objects, all orbiting in the inner solar system. Their findings were: published in The Astronomical Magazine.
Two of those objects, called 2021 LJ4 and 2021 PH27, have orbits that remain completely within Earth’s orbit. That means, pending unforeseen outages, there’s little to no risk of them ever making their way to our home base. But there was another object, one that could potentially cause problems.
Astronomers named it 2022 AP7, an asteroid nearly a mile in diameter and the largest potentially dangerous asteroid discovered in the past eight years. Not only does it hang in the inner solar system, closer to our home than we’d like, but its orbit also intersects Earth’s, opening up the possibility that the two might someday interact. If it ever does, we could be in trouble. An object of that size would cause damage across multiple continents. It’s not big enough to wipe out the entire planet, but it would be a particularly bad day.
Lucky for us, it’s unlikely to hit. Sure, its orbit crosses Earth’s path, but so do many objects. The orbits are large and the solar system is larger, even inland. Asteroids, and even planets, pale in comparison to the size of the paths they take, and the chances of two intersecting at the same time are slim. That said, we’re happy to know that 2022 AP7 exists, and continued research could identify other potential planet killers lurking in the sun’s glare.
Knowing the threats exist is the first step in planetary defense. We can only tackle what we see coming, and the work done with the Dark Energy Camera is broadening our cosmic view. As we follow it, if 2022 AP7 or any other object ever starts to get spicy, maybe we can do something about it.
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