Two faint objects hiding in archival infrared sky maps now sit at the center of a growing scientific argument about whether a massive, unseen planet orbits far beyond Neptune. Researchers mining data ...

Astronomers have discovered a new member of a rare and mysterious class of solar system objects known as sednoids - a subset of extreme trans-Neptunian objects (ETNOs) with exceptionally distant, ...

An international collaboration has discovered two of the lowest-density giant planets ever detected. The study describes rare "super-puff" planets with densities lower than candy floss. Led by the ...