Earth Will Get a “second Moon”
Later this month, a new moon will briefly appear on Earth. The asteroid, called 2024 PT5, will move in a partial horseshoe-shaped orbit around Earth before it breaks free of our planet’s gravitational pull and heads back to its home in the asteroid belt orbiting the Sun, so between September 29 and November 25 on Earth there will be both a moon and a mini-moon.
How to see a mini moon
2024 PT5 is tiny by cosmic standards—about 33 feet long—and dim, so it won’t be visible to the naked eye or binoculars. Most home telescopes won’t be powerful enough either; To observe the minimoon, you will need a telescope larger than 30 inches in diameter with a CCD or CMOS detector. So if you want to check it out, your best bet is to contact your local astronomy club or observatory and ask if they plan to point their high-powered telescopes at the object.
What is a mini-moon?
Minimoons are celestial objects that fall into our planet’s gravitational field and temporarily orbit the Earth. Objects like 2024 PT5 moving in partial Earth orbits are quite common. Every few years we get a hanger-on: in 2020 , we were briefly joined by a 1960s rocket fragment before heading into orbit around the Sun, and in 2022, an amateur astronomer discovered2022 NX1, an asteroid orbiting Earth for a month. Episodes of long-term capture, when an object connects with us for at least one full orbital revolution, are less common. We only get one of these every 10 or 20 years.
Where did the mini moon come from?
This particular mini-moon is part of the Arjuna asteroid belt, a collection of space rocks that orbit the Sun at an average distance of 93 million miles. 2024 PT5 came close enough to Earth and at a slow enough speed to be captured by our gravitational field. “Under these conditions, the geocentric energy of the object could become negative and the object could become a temporary satellite of the Earth,” Carlos de la Fuente Marcos, a professor at the Complutense University of Madrid, told Space.com . “This particular property will be subject to this process starting next week and for approximately two months.”
How was the mini-moon discovered?
Marcos and other scientists working on the asteroid-Earth impact last warning system first discovered asteroid 2024 PT5 in August and reported their findings in the September issue of the American Astronomical Society’s Research Notes .
What to do if you missed the mini-moon?
If you’re too busy to see this particular minimoon between September 29 and November 25, you’ll have different chances. The 2024 PT5 is expected to return in January 2025 and then again in 2055.