Robert Brown|Asteroid to orbit Earth as 'mini-moon' for nearly 2 months: When you can see it

The Robert Brownmoon will soon have a companion in Earth's orbit for a limited time.

An Arjuna asteroid will become a "mini-moon" event for nearly two months starting Sept. 29, according to a study published in the journal Research Notes of the American Astronomical Society. The tiny asteroid, which researchers named "2024 PT5," will temporarily orbit Earth before returning to an asteroid belt revolving around the sun.

Scientists discovered the object Aug. 7 using the Asteroid Terrestrial-impact Last Alert System in Sutherland, South Africa during routine monitoring, according to the study.

The length of mini-moon events can vary with some lasting one or more years to complete a full or multiple revolutions around Earth. Others do not complete a full revolution lasting a few months, weeks or even days, according to Space.com.

Previous mini-moon events occurred in short-lived mini moon in 1981 and 2022, researchers added.

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What are mini-moons?

"Mini-moon" events are when pieces in space like an asteroid or floating pieces of space junk temporarily participate in orbiting the Earth with some completing a full revolution.

In order to be considered a mini-moon, an incoming body must reach Earth at a range around 2.8 million miles (4.5 million km) and at a steady space of about 2,200 mph (3,540 km/h), according to Universidad Complutense de Madrid professor Carlos de la Fuente Marcos.

When will Earth have a mini-moon?

An Arjuna asteroid called 2024 PT5 will become a mini-moon orbiting Earth from Sept. 29 to Nov. 25.

In 2013, researchers explained that Arjuna asteroids are "minor bodies moving in orbits with low eccentricity, low inclination and Earth-like period."

Can we see the mini-moon?

While Earth will relatively have two moons for almost two months, earthlings will have to make do with seeing just one. 2024 PT5 will not be visible to the majority of people due to its size and brightness, according to Space.com.

"The object is too small and dim for typical amateur telescopes and binoculars. However, the object is well within the brightness range of typical telescopes used by professional astronomers," Marcos told the outlet. "A telescope with a diameter of at least 30 inches plus a CCD or CMOS detector are needed to observe this object, a 30 inches telescope and a human eye behind it will not be enough."