Skip to main content
  1. Home
  2. Space
  3. News

Gaia data shows hundreds of tiny moons orbiting around asteroids

By
gaia asteroid binaries mapping the stars of milky way pillars 1
ESA/ATG medialab; background: ESO/S. Brunier

There are plenty of moons orbiting around the planets in our solar system — Saturn, for example, has well over 100 known moons — and astronomers believe that planets outside our solar system almost certainly have moons too, called exomoons. Those are particularly hard to spot, but now researchers have a new bevy of a different type of moon to explore: those that orbit around asteroids.

It seems funny to think of it, but it’s actually quite common for asteroids to have tiny moons of their own. These form what is called a binary asteroid, like the famous pair of Didymos and Dimorphos, which NASA crashed a spacecraft into in 2022. The new data about binary asteroids comes from the European Space Agency’s Gaia mission, a space-based telescope that has spotted new potential moons around 350 asteroids.

Recommended Videos

“Binary asteroids are difficult to find as they are mostly so small and far away from us,” said lead researcher Luana Liberato of Observatoire de la Côte d’Azur, France in a statement. “Despite us expecting just under one-sixth of asteroids to have a companion, so far we have only found 500 of the million known asteroids to be in binary systems. But this discovery shows that there are many asteroid moons out there just waiting to be found.”

This image shows the orbits of the more than 150 000 asteroids in Gaia’s data release 3, from the inner parts of the Solar System to the Trojan asteroids at the distance of Jupiter, with different colour codes. The yellow circle at the centre represents the Sun. Blue represents the inner part of the Solar System, where the Near Earth Asteroids, Mars crossers, and terrestrial planets are. The Main Belt, between Mars and Jupter, is green. Jupiter trojans are red.
This image shows the orbits of the more than 150 000 asteroids in Gaia’s data release 3, from the inner parts of the Solar System to the Trojan asteroids at the distance of Jupiter, with different color codes. The yellow circle at the center represents the Sun. Blue represents the inner part of the Solar System, where the Near Earth Asteroids, Mars crossers, and terrestrial planets are. The Main Belt, between Mars and Jupiter, is green. Jupiter trojans are red. ESA/Gaia/DPAC; CC BY-SA 3.0 IGO; ACKNOWLEDGEMENTS P. Tanga (Observatoire de la Côte d'Azur)

Gaia is on a mission to map the entire Milky Way in 3D, but during its observations it also collects a large amount of data about objects within our solar system. It is this solar system data that has turned up the many new potential asteroid binaries. If these are confirmed, it would almost double the number of known asteroid binaries for astronomers to explore.

Gaia is able to detect hints of these binaries by looking for a distinctive “wobble” in the orbits of larger asteroids, which implies the existence of a smaller binary partner. Gaia is still collecting data, with another large-scale data release coming in 2026 that will uncover even more asteroid orbits.

“Gaia has proven to be an outstanding asteroid explorer, and is hard at work revealing the secrets of the cosmos both within and beyond the Solar System,” says Timo Prusti, project scientist for Gaia at ESA. “This finding highlights how each Gaia data release is a major step up in data quality, and demonstrates the amazing new science made possible by the mission.”

The research is published in the journal Astronomy & Astrophysics.

Editors’ Recommendations

Topics
Georgina Torbet
Georgina Torbet
Space Writer
Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…
Saturn’s tiny moon, Mimas, hosts an unexpected ocean beneath an icy shell
An illustration of Mimas orbiting Saturn.

When looking for places that could potentially harbor life in our solar system, astronomers are increasingly interested in some of the moons of large gas giant planets. Saturn's moon Enceladus and Jupiter's moon Europa, for example, are both top targets of habitability research because even though they are far from the sun, they are thought to host liquid water oceans beneath a thick, icy crust. Now, a new moon may join these ranks, as researchers have found evidence of an ocean beneath the icy shell of Saturn's small moon Mimas.

Mimas film

Read more
NASA automated system predicts asteroid impact over Germany
This map shows the location where the small asteroid 2024 BX1 harmlessly impacted Earth’s atmosphere over Germany, about 37 miles (60 kilometers) west of Berlin, on Jan. 21. A NASA system called Scout predicted the impact time and site within 1 second and about 330 feet (100 meters).

Earth is frequently bombarded by small asteroids, which burn up harmlessly in the atmosphere. However, identifying and tracking these asteroids is an important step in protecting the Earth against the threat of larger and potentially more dangerous impacts. NASA recently predicted the impact of a small asteroid that struck Germany using its impact prediction system, Scout.

"A small asteroid about 3 feet (1 meter) in size disintegrated harmlessly over Germany on Sunday, Jan. 21, at 1:32 a.m. local time (CET)," NASA wrote in an update. "At 95 minutes before it impacted Earth’s atmosphere, NASA’s Scout impact hazard assessment system, which monitors data on potential asteroid discoveries, gave advance warning as to where and when the asteroid would impact. This is the eighth time in history that a small Earth-bound asteroid has been detected while still in space, before entering and disintegrating in our atmosphere."

Read more
NASA cracks open its first sample from an asteroid, foiling two sticky screws
NASA’s OSIRIS-REx curation engineer, Neftali Hernandez, attaches one of the tools developed to help remove two final fasteners that prohibited complete disassembly of the TAGSAM (Touch-and-Go Sample Acquisition Mechanism) head that holds the remainder of material collected from asteroid Bennu. Engineers on the team, based at NASA’s Johnson Space Center in Houston, developed new tools that freed the fasteners on Jan. 10.

NASA returned its first sample of an asteroid to Earth last year, landing a sample collected from asteroid Bennu in the Utah desert in September. Researchers were able to extract 70 grams of material from the canister that had been carried back to Earth by the OSIRIS-REx spacecraft, making this the largest asteroid sample ever brought to Earth. The scientists involved knew there was more material inside the mechanism, but getting at it proved difficult -- until now, as NASA has announced it has now managed to open up the troublesome mechanism.

You might think it would be an easy job to unscrew a canister and dump out the material inside, but extraction was a lengthy and technical process. That's because the focus was on preserving as much of the precious sample as possible, trying not to let any of the particles get lost. The issue was with two of the 25 fasteners that held the sample inside the collection mechanism.  The mechanism is kept inside a glove box to prevent any loss, and there were only certain tools available that worked with the glove box. So when the fasteners wouldn't open with the tools they had, the team couldn't just go at them with any other tool.

Read more