# A Massive Cosmic Object Could Redefine What a Moon Is Astronomers may have to rethink the line between moons and planets. - **Source:** [Scientific American Content: Global](https://brifing.si/source/4f066134-e06d-4415-87ef-305e3dc2aba6) - **Published:** 2026-07-22 - **Topic:** [Data & AI](https://brifing.si/c/data-ai) - **Original article:** - **On Brifing:** https://brifing.si/s/980ae68e-85fa-4b09-8ffa-08ff8b5d98fd ## Moon or Planet? A massive object orbiting the brown dwarf CD-35 2722 B is forcing astronomers to reconsider the definitions of moons and planets. This object, with 90% of Jupiter's mass, behaves like a moon but resembles a planet in size. ## The Mystery of Brown Dwarfs Brown dwarfs are considered an 'intermediate class' between stars and planets. CD-35 2722 B is a typical example of this class, and the massive object orbiting it pushes the boundaries of this classification. ## Radial Velocity Analysis Astronomers used radial velocity analysis to discover the object around CD-35 2722 B. This technique measures small fluctuations in a star's motion to detect hidden satellites. ## The Significance of the Discovery This discovery may lead astronomers to revisit the definitions of moons and planets. The object around CD-35 2722 B shows how blurry such classifications can be. ## Future Discoveries With the advancement of astronomical instruments, more small and strange objects are expected to be discovered. This will require astronomers to clarify the definitions of moons and planets. ## The Concept of Exosatellites Astronomers suggest using a more neutral term like 'exosatellite' for such objects. This term could help better define the blurry boundaries between moons and planets. ## Sources covering this story - https://www.scientificamerican.com/article/a-huge-cosmic-object-could-force-astronomers-to-rethink-what-a-moon-is/ — --- _Summary written by Brifing from the original reporting. Copyright in the original article belongs to its publisher; read the full piece at the link above._