First moon found beyond solar system is as big as a planet
Astronomers reported CD-35 2722 B, a Jupiter-mass-scale companion on a ~170-day oval orbit around a brown dwarf, blurring the moon–planet boundary using radial-velocity data.
- Radial-velocity measures periodic Doppler shifts in a host object's spectral lines to infer an orbiting companion.
- CD-35 2722 B is reported as an intermediate case between moon-like and planet-like companions, based on its estimated mass and orbital behaviour.
- Astronomers estimate the orbital period by matching the repeating pattern in the measured spectral-line motion.
What happened: radial-velocity detection of a large companion around a brown dwarf
Astronomers reported detecting a large companion orbiting a brown dwarf using the radial-velocity technique, which infers the presence of an orbiting body by measuring periodic shifts in a host object’s spectral lines. The companion is designated CD-35 2722 B.
UPSC can treat CD-35 2722 B as a case study for how indirect measurements (radial-velocity periodicity) yield orbital period and mass-related estimates, and how intermediate inferred properties complicate moon-versus-planet classification. The exam focus should be on evidence-to-inference reasoning from orbital motion signals rather than direct imaging.