A piece of space debris will become a mini-moon for the Earth this weekend. Cincinnati Observatory Astronomer Wes Ryle says it's basically an asteroid that's been captured by our gravity.
“There’s actually a whole class of asteroids that have orbits that are very similar to Earth’s. They take about a year to go around the sun, just like the Earth does,” he says. “And in this case, this asteroid — which has the very interesting name, 2024 PT5 — it’s going to just drift a little bit too close to the Earth so that the Earth’s gravitational pull overcomes the sun’s gravitational pull.”
It won't last. Ryle says 2024 PT5 will be drawn away from the Earth after a couple of months.
“A lot times when an asteroid passes by, it’s whizzing by us at high speed and kind of uses Earth’s gravity to deflect it on its path around the sun,” Ryle says. “But in this case, it’s a very slow encounter, and so just a gradual nudge closer to the Earth makes it interact with the Earth a little bit, but then the sun’s gravity is able to overcome it just in this case two months later.”
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Ryle says 2024 PT5 is only about 33-feet across.
“Even with a decent sized telescope — the kinds that are available to most amateur astronomers — you’re still not going to be able to see it,” he says. “But professional astronomers will be able to use much larger ‘scopes, like say, 30 inches, 40 inches or bigger, along with cameras in order to take images of it.”
Ryle says it's too small for the Observatory's telescope.
He says there may be something else on the horizon. There's a comet rounding the sun now that astronomers have been watching for a while.
“It’s always dangerous to get your hopes up too much for a comet, but if this one pans out, it could be something that would be visible with our ‘scopes in mid-October.”
This comet has a couple of names: Tsuchinshan, named for a team of Chinese astronomers; and ATLAS, for the Asteroid Terrestrial-impact Last Alert System, which scans the skies for near-Earth objects.
“There was some fear that it was going to disintegrate as it went around the sun and so wasn’t going to produce a good show,” Ryle says. “But up at least until now, it has held together and has been brightening. There’s been some talk of ‘this could be the comet of the century’ but those statements can always be very much overblown.”
Ryle says it's coming up with the sun now, and by the end of October will be in the sky at sunset. At the moment, it is not visible to the naked eye.
