Earth will have a mini-moon in the form of an asteroid from September 29 to November 25 of this year. This asteroid, named 2024 PT5, will enter Earth’s orbit during this time period before continuing on its way out into the solar system. The asteroid was discovered by the ATLAS group in August and is expected to be a genuine asteroid rather than random space junk. Mini-moons are not uncommon occurrences, with Earth experiencing them almost every year due to various asteroids entering its orbit for short periods of time.
Despite the excitement surrounding the arrival of the mini-moon, it is unlikely that it will be visible to the naked eye. NASA reports that the absolute magnitude of 2024 PT5 is 27.593, making it too dim for amateur astronomers to see without a powerful telescope. Mini-moons have been observed before, with some being bright enough to be visible with amateur astronomy instruments. Some asteroids even make repeated visits as mini-moons, with instances of them orbiting Earth for years at a time. The consistent occurrence of mini-moons has led some researchers to believe that Earth always has one in its orbit at any given time.
A simulation of the asteroid’s path posted by amateur astronomer Tony Dunn shows that 2024 PT5 will have a geocentric energy that remains negative for 56.6 days. The orbit of the asteroid is depicted in the simulation as a red line, circling only about 25% of the Earth before continuing on its trajectory. Some astronomers refer to this type of mini-moon as a temporarily captured flyby, as the asteroid will not complete a full orbit of Earth. Mini-moons that do complete a full orbit are known as temporarily captured orbiters.
The upcoming mini-moon is part of a series of mini-moons that Earth has experienced in previous years. These mini-moons are often caused by asteroids entering Earth’s orbit for short periods of time before continuing on their path through the solar system. Some mini-moons have been identified as pieces of space junk or rocket boosters from past launches. The consistent appearance of mini-moons has intrigued researchers and amateur astronomers alike, with some even making repeat visits over several years. While Earth will have a mini-moon in the form of the asteroid 2024 PT5 this year, it is unlikely to be visible without the use of a telescope.
