There may be a new bright comet in the night sky, but this weekend Earth also has a new moon. As of Sunday, Sept. 29, 2024, our planet’s gravitational pull has captured a space rock and sent it into orbit around Earth.
What Is A ‘Mini-Moon’?
Technically a “temporarily captured object,” 2024 PT5 is a near-Earth asteroid and Earth’s newest mini-moon. This 11-meter diameter near-Earth asteroid — about the same as a London bus — is expected to stay in orbit for a couple of months before resuming its own journey through the solar system on Nov. 25.
How To See Earth’s New ‘Mini-Moon’
It’s a unique and fleeting opportunity for astronomers to study it, though there are only 57 days in which to do so. At a magnitude of 22, it’s also going to be very faint, with large professional 30-inch telescopes likely necessary to catch a glimpse of the rare object. It won’t be visible to the naked eye or backyard telescopes.
Who First Found Earth’s New ‘Mini Moon’?
Discovered on Aug. 7 by the Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope in Sutherland, South Africa, 2024 PT5 is a member of the Arjuna asteroid group and is known as a near-Earth asteroid (NEA). Arjuna asteroids orbit the sun along an orbital path slightly farther out into the solar system than Earth’s orbital path. Some make close approaches to the Earth-moon system.
Earth’s Other ‘Mini Moons’
2024 PT5 is not the first “mini-moon” that Earth has collected. In fact, Earth has been known to capture and pull NEOs into its orbit, giving rise to quasi-satellites.
In February 2020, an object called 2020 CD3 was discovered to have been in orbit for a few years and departed in early March 2020. Discovered in 2016, an object called 2016 HO3 — and also Kamo’oalewa, meaning “the oscillating celestial fragment” in Hawaiian — was found to be 130 to 330 feet (40 to 100 meters) in diameter.
However, it was not a moon, strictly speaking, because it wasn’t in orbit of Earth. Instead, it moved in sync with Earth in a 1-to-1 resonance, creating the illusion of orbiting our planet while actually orbiting the sun.
Wishing you clear skies and wide eyes.
