Starting on September 29, 2024, Earth will briefly gain a second moon as asteroid 2024 PT5 gets captured by our planet’s gravity. While it’s no match for the grandeur of the Moon, this asteroid, measuring about 33 feet (10 meters) in diameter, will act as a “mini-moon” for approximately two months. Discovered on August 7, 2024, by the Asteroid Terrestrial-Impact Last Alert System (ATLAS) in South Africa, this asteroid will temporarily loop around Earth before continuing its journey through the solar system.
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Researchers Carlos and Raúl de la Fuente Marcos from the Complutense University of Madrid have carefully tracked the path of 2024 PT5, revealing its temporary capture by Earth’s gravity. While the mini-moon will not complete a full orbit, it will remain in our planet’s gravitational pull until November 25, 2024, before breaking free and resuming its orbit around the sun.
What is a Mini-Moon?
Mini-moons are celestial objects, such as small asteroids, that are temporarily caught in Earth’s gravitational field. These objects do not maintain a stable orbit around the planet and eventually escape. While Earth permanently hosts a single, large moon, mini-moons are rare but have been observed before.
The term “mini-moon” refers to the temporary nature of these objects’ orbits. When an asteroid comes close enough to Earth at the right speed and trajectory, it can be briefly captured by our planet’s gravity. After a short stint, the asteroid usually breaks free, continuing its orbit around the sun. This is the case with asteroid 2024 PT5.
Arjuna Connection
The asteroid 2024 PT5 likely belongs to a group of near-Earth objects known as the Arjuna asteroids, which share orbits around the sun similar to Earth’s. These asteroids are named after a legendary prince from the Mahābhārata, an ancient Indian epic. Researchers suggest that 2024 PT5’s low velocity and proximity to Earth allowed it to be temporarily captured by the planet’s gravitational pull.
Asteroids like 2024 PT5 offer scientists a unique opportunity to study the gravitational dynamics between Earth and smaller celestial bodies. Their unpredictable paths also help astronomers refine their models of asteroid movement, which can be crucial for planetary defense strategies in the event of a more hazardous object approaching Earth.
Too Dim to See
Despite the excitement surrounding Earth’s new mini-moon, 2024 PT5 will be too dim for most telescopes to capture. With a magnitude of 22, it will remain invisible to the naked eye and even to most backyard telescopes. Only advanced observatories will be able to track its movements using radar and other technologies.
Amateur astronomers will miss out on seeing the mini-moon, but astronomers will be closely monitoring its path for the valuable insights it offers. The study of mini-moons like 2024 PT5 helps scientists understand how Earth’s gravity interacts with near-Earth objects.
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While 2024 PT5’s visit is brief, lasting only 56.6 days, it represents a significant scientific event. By observing how the asteroid’s orbit is altered by Earth’s gravity, researchers gain insights into the behavior of other asteroids that may pass close to our planet. The study of mini-moons could one day play a role in space exploration missions, such as asteroid mining.