A moon beyond our solar system
Astronomers have found a new exomoon candidate circling a brown dwarf in the stellar system CD-35 2722. The object is roughly the mass of a planet, making it one of the most unusual moon candidates ever detected.
The system is built around a star with about half the mass of our Sun. A brown dwarf, an object too heavy to be a planet but too light to ignite as a star, orbits that star. The newly found exomoon circles the brown dwarf in turn.
The discovery was made using data from ground-based observatories. Researchers tracked a subtle dip in the brown dwarf's light, a pattern that repeats at regular intervals and points to an orbiting companion.
How moons form around failed stars
Brown dwarfs sit in a strange middle ground between planets and stars. They form like stars, from collapsing clouds of gas and dust, but they never reach the mass needed to start fusion.
Scientists have long debated whether brown dwarfs can host moons. The new candidate suggests they can, and that such moons can grow to planetary size. If confirmed, the finding would show that moon formation is not limited to ordinary stars.
The object's size is what makes it remarkable. Most known exomoons are smaller than Earth. This candidate is closer in mass to a giant planet, which challenges current models of how moons take shape.
What comes next
Follow-up observations are already planned with larger telescopes. Astronomers want to confirm the object's orbit and rule out other explanations for the repeating light pattern.
The discovery adds to a growing catalog of strange worlds beyond our solar system. As telescope technology improves, researchers expect to find many more exomoons, and to learn how common they really are. Each new candidate brings astronomers closer to understanding where and how moons can form across the galaxy.