Our moon is about to get a temporary companion in Earth’s orbit.

An asteroid known as Arjuna will take on the role of a “mini-moon” for nearly two months starting September 29, as detailed in a study published in the journal Research Notes of the American Astronomical Society. This small asteroid, designated “2024 PT5,” will orbit Earth for a short time before heading back to its usual spot in an asteroid belt around the sun.

The discovery of this asteroid took place on August 7, made by researchers utilizing the Asteroid Terrestrial-impact Last Alert System in Sutherland, South Africa, during their routine observations.

The duration of mini-moon occurrences can range significantly. Some may last a year or longer, completing one or multiple orbits around Earth. Others may only last for a few months, weeks, or even just days, as per information from Space.com.

Earlier mini-moon events were noted briefly in 1981 and 2022, the researchers highlighted.

What are mini-moons?

Mini-moon events occur when celestial objects, like asteroids or fragmented space debris, temporarily enter Earth’s orbit, with some managing to complete a full circuit.

To qualify as a mini-moon, the approaching body must come within approximately 2.8 million miles (4.5 million km) of Earth and travel at a consistent speed of around 2,200 mph (3,540 km/h), according to Carlos de la Fuente Marcos, a professor at Universidad Complutense de Madrid.

When will Earth have a mini-moon?

Asteroid 2024 PT5 is set to become a mini-moon orbiting our planet from September 29 to November 25.

In 2013, researchers characterized Arjuna asteroids as “minor bodies moving in paths with low eccentricity, low inclination and Earth-like periods.”

Will we be able to see the mini-moon?

Even though Earth will have an additional moon for nearly two months, most people will likely not observe 2024 PT5. Its small size and dimness mean it’s not easily visible to the average observer, as reported by Space.com.

“The object is too tiny and faint for common amateur telescopes and binoculars. However, it falls within the visibility range of professional astronomers’ telescopes,” explained Marcos. “To observe this object, you would need a telescope with a minimum diameter of 30 inches, along with a CCD or CMOS detector; just a 30-inch telescope alone with the human eye will not suffice.”