Latest news with #minimoons
Daily Mail
2 days ago
- Science
- Daily Mail
Earth has over 6 moons you never knew about, scientists reveal
If you thought the Earth only had one moon, think again. Researchers have revealed that our planet may actually have an entire collection orbiting us at any given time. A new study has found that Earth has at least six 'minimoons' in orbit on a regular basis, with most of them being smaller pieces of the actual moon we see in the sky each night. A team from the US, Italy, Germany, Finland, and Sweden said these tiny satellites are generally around six feet in diameter and were formed by asteroids impacting on the moon's surface. The collisions essentially kick up a bunch of dust and moon debris, with some of it being large enough to float away and get pulled into the Earth's gravitational field. The study suggested that these broken moon pieces, known as 'lunar ejecta,' can move into somewhat stable orbits, staying near Earth for years. Minimoons typically stay in Earth's orbit only for a short time before escaping or, in rare cases, hitting our planet or the moon. Most of the time, these temporarily bound objects (TBOs) break away from Earth and are pulled into the sun's gravity, where they'll remain indefinitely, while new chunks of the moon are broken off to replace them. Robert Jedicke, a researcher at the University of Hawaii, said: It's 'kind of like a square dance, where partners change regularly and sometimes leave the dance floor for a while.' 'Given that 18 percent of TBOs can also be classified as minimoons, our nominal results suggest that there should be about 6.5 minimoons larger than 1 m diameter in the [Earth-Moon system] at any time,' the researchers wrote in their new report. The new study could upend the belief among scientists that these minimoons which quietly circle Earth all come from the solar system's asteroid belt. A 2018 study suggested most TBOs come from this distant region which sits between Mars and Jupiter. However, the new findings published in Icarus looked at two recently discovered minimoons, Kamo'oalewa and 2024 PT5, which both appear to have telltale signs of being moon fragments. Specifically, Kamo'oalewa, discovered in 2016 by the Pan-STARRS1 telescope in Hawaii, was found to reflect light in a way that closely matches the moon's surface composition. The large minimoon, which measures between 131 to 328 feet in diameter, also has the same composition of lunar rocks, rich in silicates. This greatly differs from the typical asteroid, which often contains different minerals and metals than those found on the moon. Jedicke told that 2024 PT5, which was discovered entering Earth's orbit on August 7, 2024, has exhibited the same lunar-like characteristics. Last year, 2024 PT5 was dubbed Earth's temporary 'second moon' because of its size and lingering presence so close to our planet. Astronomers collected data on the supposed asteroid as it circled Earth, which led astronomers to suggest that it may have been a chunk of our moon instead. The leading theory of lunar formation is called the 'giant impact hypothesis,' which theorizes that the moon is actually an enormous, orbiting hunk of Earth. According to this theory, our planet collided with a Mars-sized planet roughly four billion years ago, and this triggered an explosion of material from Earth that shot into space and eventually condensed to form the moon. If the giant impact hypothesis and the analysis of 2024 PT5's origin are correct, that would mean our true moon is the parent of this minimoon, and Earth is its grandparent.
Yahoo
15-07-2025
- Science
- Yahoo
Earth may have at least 6 'minimoons' at any given time. Where do they come from?
When you buy through links on our articles, Future and its syndication partners may earn a commission. Half a dozen fragments of the moon may briefly orbit Earth at any given time, before moving on to circle the sun, new research suggests — but the minimoons' small size and quick pace make them challenging to spot. When objects collide with the moon, they send up a shower of material, some of which manages to escape into space. Although there may be an occasional large chunk, most are fast-moving and smaller than 6.5 feet (2 meters) in diameter. The bulk of the lunar material falls into orbit around the more gravitationally attractive sun. But some of the debris may occasionally be pulled into an orbit around Earth before returning to circle the sun, researchers explained in a study published in the journal Icarus. It's "kind of like a square dance, where partners change regularly and sometimes leave the dance floor for a while," Robert Jedicke, a researcher at the University of Hawaii and lead author of the study, told by email. Although the International Astronomical Union doesn't have an official definition, previous research suggested that a minimoon could be an object that is at least temporarily bound to Earth, makes at least one revolution of the planet, and is closer than about four times the Earth-moon distance at some point in its orbit. Minimoons can come from anywhere in the solar system, but a 2018 study suggested most come from the region of the asteroid belt, between the orbits of Mars and Jupiter. The recent appearance of minimoons from the moon, however, is calling that finding into question. In 2016, the Pan-STARRS1 asteroid survey telescope in Hawaii spotted a 131- to 328-foot-wide (40 to 100 meters) near-Earth object identified as Kamo'oalewa, or "469219 Kamo'oalewa," orbiting the sun in sync with Earth. Later studies revealed that Kamo'oalewa was a slice of the moon excavated between 1 million and 10 million years ago in the crash that formed the Giordano Bruno crater. Earlier this year, astronomers announced that a second temporary terrestrial satellite appeared to have a lunar origin. Discovered last year, the object — called 2024 PT5 — looks more like the moon than an asteroid. Together, these two objects suggest that the moon could be birthing its own tiny moons. So Jedicke and his colleagues decided to calculate just how many lunar minimoons might exist. Relying on simulations of how particles blown from the moon might behave, they found that many of the particles blasted into space could be captured at least temporarily by Earth, and about a fifth of them were likely to become minimoons. The new findings nominally predict that 6.5 lunar-born satellites may be circling Earth at a time. The individual objects are changeable; if they could be counted today, and then again in a year, some would be new objects. A typical minimoon dances around Earth for an average of about nine months, Jedicke said, and these minimoons are constantly replenished from the material traveling in an Earth-like orbit. But when it comes to nailing down the predicted number of minimoons, Jedicke cautioned that the uncertainty is "ginormous — many orders of magnitude." That's due to many unknowns, including the size of a crater formed by an impact and the size and speed distribution of the ejected material. "If there were that many [temporarily bound objects], the telescopic surveys would probably detect more of them," Jedicke said. "So the nominal prediction is almost certainly wrong. That's science." Because science builds on new information, identifications of more lunar minimoons and a better understanding of their size distribution will help to refine that prediction and provide new insight into the crater formation process. Due to their size, the tiny, temporary moons are challenging to spot. The problem relates to both their size and their speed. With most of the fragments ranging from 3 to 7 feet (1 to 2 m) in diameter, even the most seasoned instruments can struggle to detect them. Jedicke compares them to a car or an SUV. "Detecting objects in that size range means they have to be close so they are bright, but if they are close, it means they also appear to be moving quickly across the sky," Jedicke said. "It is incredible that modern telescopic surveys have the ability to detect such small objects up to millions of kilometers away." In massive sky surveys, computers usually work to pull out motion. When minimoons are close enough to be seen, their rapid motion may leave trails, rather than spots, on images of the sky. "Trails are more difficult for computer algorithms to identify," Jedicke said. RELATED STORIES —Newborn moon may have had many mini-siblings in Earth orbit long ago —Earth's mini-moon has finally departed. Will it ever return as a 'second moon?' —NASA raises the odds that an asteroid could hit the moon in 2032 But all is not lost. The new research suggests that 2020 CD3 was visible to the Catalina Sky Survey on only two of the roughly 1,000 nights the object was in range. The successful detection bodes well for future observations. Once the objects have been identified, tracking becomes easier because astronomers know where and when to look for the minimoons. These brief visitors could also have intriguing commercial applications, since they would require the least amount of fuel to visit, Jedicke said. Instead of flying to the asteroid belt to extract water, minerals and other commercially desirable elements, companies could find ways to snag the transients as they briefly orbit Earth. From a scientific perspective, minimoons and their kin "may help reveal how the solar system formed and continues to evolve," Jedicke said. Understanding how lunar debris was flung off of the moon during an impact can help researchers better understand and estimate damage due to asteroid impacts on Earth.
