Astronomers have uncovered two of the lightest worlds ever detected—giant exoplanets so ethereal that their density is lower than candy floss. Each world is roughly the size of Jupiter yet contains remarkably little mass, making them extraordinarily insubstantial.
The sibling planets orbit the same distant star, locked in a gravitational dance that causes them to tug each other off schedule. Their extreme lightness was measured from the depths of an Antarctic winter, using observations that allowed scientists to weigh them precisely.
Both exoplanets share a single planetary system, and their faint pull on one another provided the key data needed to calculate their densities. The findings raise a pressing question: how does a planet end up barely heavier than air?
The discovery challenges existing models of planetary formation. Researchers now aim to understand the processes that could yield such puffed-up worlds, which hold almost nothing inside despite their Jupiter-like dimensions.
While the findings are significant, the study relies on indirect measurements of planetary mass and density. Confirmation from additional telescopes or future missions will be needed to fully verify the internal composition of these unusual objects.