The Earth will gain a second moon this Sunday, on September 29, when a tiny asteroid comes into orbit – but only briefly.
The 2024 PT5 is set to come close to Earth, according to space.com, and will leave after two months to rejoin an asteroid belt that passes around the sun.
Researchers at Universidad Complutense de Madrid study what are known as mini-moon events and reported this latest find on Tuesday (September 17).
Professor Carlos de la Fuente Marcos said: "The object that is going to pay us a visit belongs to the Arjuna asteroid belt.
“[This is] a secondary asteroid belt made of space rocks that follow orbits very similar to that of Earth at an average distance to the sun of about 93 million miles.”
The 2024 PT5 is only 10 metres long (compared with the 1,737.5-kilometre radius of the moon) and will be in orbit from September 29 to November 25, reported the Metro.
This will make it almost impossible to see it in the sky.
Paul Chodas, the director of the Center for Near Earth Object Studies at Nasa’s Jet Propulsion Laboratory, told the New York Times that PT5 is “possibly a piece of ejecta from an impact on the moon”.
This means that PT5 could be formed of ancient fragments of the Earth’s moon.
Prof Marcos explained that mini-moon events are either when an asteroid completes one or more revolutions of the Earth — or a shorter engagement when one orbit is not reached.
Lance Benner, of the Jet Propulsion Laboratory has, however, lowered excitement by saying that its horse-shoe-shaped trajectory of the Earth means it may not have moon status.
“It certainly won’t complete one full revolution in the Earth-moon system this [autumn], so I’m not sure I would classify it as a mini-moon,” he said.
Prof Marcos added: "It will not follow a full orbit around Earth.
"You may say that if a true satellite is like a customer buying goods inside a store, objects like 2024 PT5 are window shoppers."
Nasa's Asteroid Terrestrial-Impact Last Alert System (Atlas) detected the asteroid for the first time on August 7.
Is it possible to see the second moon?
Not by most of us, no. Unfortunately, during its occupation around Earth, 2024 PT5 won't be visible to the vast majority of sky watchers.
"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," Prof Marcos explained.
"A telescope with a diameter of at least 30in plus a CCD or CMOS detector are needed to observe this object; a 30in-telescope and a human eye behind it will not be enough."
