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NDTV
04-05-2025
- Science
- NDTV
'Minimoons': Rocks Circling Near Earth Could Be A Chunk Of The Moon
A whole population of 'minimoons' - tiny natural satellites - may be quietly circling near Earth, scientists now believe, after discovering a second Moon-origin rock drifting close to our planet. The newly observed object, named 2024 PT5, was spotted near Earth last August and is thought to be a lunar fragment, possibly blasted off the Moon during a massive impact long ago. This makes it only the second known piece of the Moon found orbiting in near-Earth space. "If there were only one object, that would be interesting but an outlier," said Teddy Kareta, a planetary scientist at Lowell Observatory in Arizona. "If there's two, we're pretty confident that's a population." The findings were published in The Astrophysical Journal Letters in January and presented in March at the 56th Lunar and Planetary Sciences Conference in Texas. 2024 PT5 stood out when it was first observed by astronomers in South Africa, thanks to its unusually slow movement, just 2 metres per second relative to Earth. That made it a promising candidate for the Mission Accessible Near-Earth Object Survey (MANOS), which focuses on finding asteroids that are easiest to reach with spacecraft. The rock, just 26 to 39 feet (8 to 12 metres) wide, didn't look like a typical asteroid. Mr Kareta and his team believe it may have been ejected from the Moon's surface during a violent impact. The discovery suggests that other such fragments might be hiding in near-Earth space. Earth regularly travels through a cloud of debris, both natural and man-made, as it orbits the Sun. Some of it is leftover rock from the early solar system, and scientists keep a close eye on these near-Earth objects (NEOs) in case any pose a threat. Material that gets blasted off the Moon during an impact usually stays close to Earth's orbit, especially the slower pieces. 2024 PT5 was briefly called a minimoon in September because it moved alongside Earth for a short time. But it didn't stay for long and eventually drifted away. Scientists think it will come close to Earth again in 2055. Within a week of the discovery, Mr Kareta and MANOS principal investigator Nick Moskovitz turned the Lowell Discovery Telescope toward 2024 PT5. After analysing the rock in visible and near-infrared light, they found its composition closely resembled moon rocks brought back by the Apollo missions and the Soviet Luna 24 mission. "It's like realising a crime scene has a totally new kind of evidence you didn't know you had before," Mr Kareta told "It might not help you solve the crime right away, but considering the importance of the task, new details to compare are always welcome." This is only the second known lunar fragment spotted in near-Earth space. The first, called Kamo'oalewa, was discovered in 2016 and linked to the Moon in 2021.
Yahoo
03-05-2025
- Science
- Yahoo
A whole 'population' of minimoons may be lurking near Earth, researchers say
When you buy through links on our articles, Future and its syndication partners may earn a commission. Earth's minimoon may be a chip off the old block: New research suggests that 2024 PT5 — a small, rocky body dubbed a "minimoon" during its discovery last year — may have been blown off the moon during a giant impact long ago, making it the second known sample traveling near Earth's orbit. The discovery hints at a hidden population of lunar fragments traveling near Earth. "If there were only one object, that would be interesting but an outlier," Teddy Kareta, a planetary scientist at Lowell Observatory in Arizona, said in March at the 56th annual Lunar and Planetary Sciences Conference in the Woodlands, Texas. "If there's two, we're pretty confident that's a population." Earth travels through and with a cloud of debris as the planet makes tracks around the sun. Some of that material is human-made — satellites and space junk. Other material is rocky debris left over from collisions in the early solar system. These near-Earth objects (NEOs) can be a concern, so they are tracked to ensure they are not a threat to our planet. Related: Just how many threatening asteroids are there? It's complicated. In August 2024, astronomers in South Africa identified a new rock, known as 2024 PT5, traveling near Earth. 2024 PT5 was moving slowly, with a relative velocity of only 4.5 mph (2 meters per second), making it a strong target for the Mission Accessible Near-Earth Object Survey (MANOS). Only nine other asteroids have been seen traveling so slowly at their closest approach. Kareta, along with MANOS principal investigator Nick Moskovitz, also at Lowell, have been intrigued by the idea of finding moon rocks in space since just after the first such fragment was identified in 2021. MANOS is designed to hunt for and characterize the near-Earth asteroids that might be the easiest to visit with a spacecraft. According to Kareta, that meant the survey was ideal for looking at lunar castoffs. Within a week of 2024 PT5's discovery, they had turned the Lowell Discovery Telescope in the space rock's direction. After studying 2024 PT5 in both visible and near-infrared data, they concluded that it wasn't an ordinary asteroid. Its composition proved similar to that of rocks carried back to Earth during the Apollo program, as well as one returned by the Soviet Union's Luna 24. The researchers also found that 2024 PT5 was small — 26 to 39 feet (8 to 12 meters) in diameter. Kareta and his colleagues suspect that 2024 PT5 was excavated when something crashed into the moon. By studying the asteroid's composition, they hope to tie the material back to its source and perhaps even identify its parent crater. Cratering events are one of the most important processes that shape planetary bodies without tectonics or liquids to remold them. But impacts can be affected by a variety of variables, and understanding them can be a challenge. Matching debris to its crater can provide another way to understand what happens when two bodies collide. That's what makes identifying lunar rocks in space so intriguing. "It's like realizing a crime scene has a totally new kind of evidence you didn't know you had before," Kareta told by email. "It might not help you solve the crime right away, but considering the importance of the task, new details to compare are always welcome." Material from the Earth-moon system should be some of the easiest to fall into orbit near Earth. After an impactor collides with the moon, all but the fastest-moving material flung into space should continue traveling near our system. Although 2024 PT5 was dubbed a minimoon in September, it only briefly fell in line with the planet. Kareta compared it to two cars on the highway. Earth is blazing along in its own lane, while 2024 PT5 chugged along the interior path, closer to the sun. In 2024, the tiny chunk of rock changed lanes, falling into Earth's path at roughly the same speed. By the end of September, it had moved on, shifting outward. Earth left it behind, but on the solar race track, the pair should be parallel again in 2055, scientists estimate. 2024 PT5 is the second lunar fragment identified by researchers. Another small rock, Kamo'oalewa, was traced to the moon in 2021, five years after its discovery. That could hint at a new population, hidden in plain sight. Both objects are traveling in Earth-like orbits, but they don't have much else in common. Kamo'oalewa is larger and appears to have been battered by cosmic rays, solar radiation and other processes longer than 2024 PT5 has. That might suggest it has been in space longer, Kareta said. Their orbits are also a bit different. Kamo'oalewa's quasi-satellite orbit keeps it in Earth's immediate vicinity for several consecutive orbits, even though it isn't actually spinning around the planet. Unlike the lane-changing 2024 PT5, Kamo'oalewa is more like a car that stays one lane over, moving at roughly the same speed. Researchers are trying to match Kamo'oalewa to a crater. A recent study suggested that it could have come from a smashup that created Giordano Bruno crater, a 14-mile-wide (22 km) impact basin on the far side of the moon. Kareta is hopeful that more will be identified. While a single sample is an oddity, two could be part of a crowd. He suspects that some asteroids that have been identified as unusual may be lunar rocks in disguise. RELATED STORIES: —Goodnight moon! Astronomers snap photo of Earth's departing mini-moon —Earth's mini-moon has finally departed. Will it ever return as a 'second moon?' —Earth's recent asteroid visitor might've been a piece of the moon When the orbits of NEOs are calculated, their source region is often estimated based on their current travels. If some objects have been misclassified and their sources are incorrect, that could mean other aspects of their orbits are misunderstood. Although that could potentially increase the long-term chances of Earth being hit by an asteroid, Kareta said it is "almost certainly not" the case, "but we'll need to prove it." For now, Kareta and his colleagues will continue to use MANOS to search for other potential lunar fragments. He's hopeful that the doubled population will convince other researchers to take a closer look, too. Upcoming large-scale surveys — like the Vera Rubin Observatory, a ground-based telescope expected to see first light this year — should also help to reveal other dim objects. The research was published in January in The Astrophysical Journal Letters.
