2024 PT5. will pose as Earth's second moon for two months (Credit: NASA./gov/ Public Domain)

Get ready for a rare celestial event! This weekend, our planet will capture a temporary "mini-moon" in the form of a small asteroid called 2024 PT5. This tiny space rock will enter Earth's orbit on September 29, 2024. However, unlike our permanent Moon, which has been with us for billions of years, 2024 PT5 will only be around for eight weeks.

"According to the latest data available from NASA's Jet Propulsion Laboratory Horizons system, the temporary capture will start at 15:54 EDT [on September 29] and will end at 11:43 EDT on November 25," Carlos de la Fuente Marcos, a mini moon expert, told Space.com.

2024 PT5 is part of the Arjuna asteroid belt. The belt comprises millions of space rocks that orbit the Sun at a similar distance to Earth, around 93 million miles (150 million km) away. Some asteroids in this belt come as close as 2.8 million miles (4.5 million km) to Earth. Due to their slow speed, they can easily be pulled in by Earth's gravity. However, these asteroids rarely complete a full circle around our planet. After its eight-week stay, 2024 PT5 will return to its Arjuna family orbit around the Sun.

2024 PT5. is part of the Arjuna asteroid belt (Credit: Mdf/ Public Domain/ Wikimedia Commons)

Unfortunately, the mini-moon will not be visible to average skywatchers. At just 38 feet (11.5 m) wide, 2024 PT5 is too tiny to be seen with the unaided eye or a small telescope. To put it in perspective, that is about 300,000 times smaller than our permanent Moon, which has a diameter of about 2,159 miles (3,475 km).

"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 said.

This is not the first time Earth has had a temporary moon. Scientists have documented at least two "short captures" in the past decade. Each lasted about a week. There have also been two rarer "long capture" events, where the mini-moons have remained in Earth's orbit for a full year or more.

Resources: Space.com, BBC.com, CNN.com