The world is going to witness a unique celestial event, where our earth will experience a temporary second “moon,” Asteroid 2024 PT5. The event will take place later this month around September 29 and will last till November 25. The 2024 PT5 will orbit earth before returning to its journey through the solar system. The mini-moon will be captured by earth’s gravitational field for around two months.
What is 2024 PT5?
The Asteroid Terrestrial-Impact Last Alert System (ATLAS), a NASA-funded initiative to raise early warning, detected the Asteroid 2024 PT5 on August 7.
The asteroid has a diameter of around 10 metres. It will not complete its full orbit in its 53-day period near earth, but will follow a horseshoe-shaped path before leaving earth's gravitational influence.
According to the researchers Carlos de la Fuente Marcos and Raúl de la Fuente Marcos from the Universidad Complutense de Madrid, the speed, size and trajectory of asteroid 2024 PT5 are just right for earth to trap the space rock in its gravitational field.
The event also highlights earth's regular encounters with Near-Earth Objects (NEOs). This is a rare phenomenon which is also known as “temporarily captured flyby,” where asteroids enter earth's orbit but not for very long.
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The lead author and professor at Universidad Complutense de Madrid told Space.com, "The object that is going to pay us a visit belongs to the Arjuna asteroid belt, 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 (150 million kilometres)."
"Objects in the Arjuna asteroid belt are part of the near-Earth object population of asteroids and comets," he added.
Marcon explained that the 2024 PT5 will not complete a full moon 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," he said.
Event occurs for short periods of time
Mini-moon events can be classified into two types; long captures (lasting a year or more) and short captures (lasting days, weeks, or months). The events take place every 10 to 20 years, short captures like the one involving 2024 PT5 are more frequently happening several times per decade.
The gravitational influence of the sun resultantly causes these objects to be ejected from the orbit of the earth before returning to their sun-centred paths.
Most skywatchers can’t watch it
Unfortunately, the event wouldn't be easily visible with bare eyes. To observe the mini-moon, people need professional astronomers to be able to study the event with the help of larger telescopes and specialised equipment.
Marcos also stated that, "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. A telescope with a diameter of at least 30 inches plus a CCD or CMOS detector is needed to observe this object, a 30-inch telescope and a human eye behind it will not be enough," he added.