The cast of exoplanets has an extraordinary new member. Using ESO’s telescopes, astronomers have discovered an approximately seven- Jupiter-mass companion to an object that is itself only twice as ...

Astronomers are challenging an existing theoretical model and thrilling the astronomy community with their discovery of a seven-Jupiter-mass companion next to a planemo, or planetary mass object, only ...

A planemo is a planetary-mass object that never undergoes fusion, unlike stars.

The debate over the definition of planethood has been simmering for years – and it bubbled up again this week, thanks to new research into free-floating planemos, or planetary-mass objects. It turns ...