Earth is about to get a mini-moon (temporarily). What to know about asteroid 2024 PT5.

This story was updated t o add new information.

The Earth will soon have a second mini-moon, although it will be a brief visit.

Scientists wrote about the mini-moon and its anticipated orbit around Earth in a study published earlier this month in the non-peer-reviewed journal AAS Research Notes .

The small asteroid was discovered on Aug. 7 by the Asteroid Terrestrial-impact Last Alert System (ATLAS) , a NASA-funded program. Now named asteroid 2024 PT5, it will be captured in Earth's gravitational pull between Sept. 29 and Nov. 25. After that, it will escape Earth's orbit and be pulled toward the sun before continuing its travels around our solar system.

Projected path of asteroid 2024 PT5

During its 56-day orbit, Asteroid 2024 PT5 will travel in a horseshoe-shaped trajectory before leaving Earth's gravity.

It's unlikely we can catch a glimpse of the passing mini-moon as it enters Earth's gravity. The NASA JPL Small-Body Database states that 2024 PT5 won't be visible to most amateur telescopes due to its extremely low absolute magnitude of 22 , which is too dim even for backyard binoculars or telescopes.

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Where did 2024 PT5 come from?

At times, the gravitational pull of neighboring planets can bring asteroids into Earth's orbit. These small objects, such as 2024 PT5, are called Near-Earth Objects, or NEOs, according to NASA . The Center for Near Earth Object Studies (CNEOS) at NASA's Jet Propulsion Laboratory (JPL) estimates that there are more than 35,000 NEOs, and 99% of NEOs are made up of asteroids.

Researchers think 2024 PT5 came from the Arjuna asteroid belt, which is a group of small asteroids that follow dynamically cold, Earth-like orbits, according to Astronomy & Astrophysics .

How big is the mini-moon 2024 PT5?

Compared to Earth's moon, which has a diameter of 2,159 miles, asteroid 2024 PT5 is just a tiny spec measuring at about 33 feet wide. That's about the width of a city bus.

This is not the first mini-moon that Earth has had. 2024 PT5 is tracing a very similar path to asteroid 2022 NX1, which was also about 33 feet in diameter. In 1981 and 2022, the asteroid 2022 NX1 briefly orbited Earth as a mini-moon. In 2051, that asteroid will reappear as a transient mini-moon, according to EarthSky.org .

It won't be the last time we see 2024 PT5 either. It's expected to reappear in 2055, according to UniverseToday.com .

CONTRIBUTING Jim Sergent

SOURCE NASA, Asteroid Terrestrial-impact Last Alert System, EarthSky.org, UniverseToday.com, Astronomy & Astrophysics and European Space Agency

This article originally appeared on USA TODAY: Earth is about to get a mini-moon (temporarily). What to know about asteroid 2024 PT5.