Relatedly, astronomers may have just pushed the upper size limit of what counts as a planet.

Gas giants are large planets mostly composed of helium and/or hydrogen. Although these planets have dense cores, they don't ...

Deep in the older, denser reaches of the Milky Way, there is a red dwarf star that shouldn’t exist — or at least, its family ...

Gas giants possibly developed slowly in the solar system. They developed cores layer by layer within a disk of ice and dust ...

A planetary system 116 light-years from Earth has a peculiar pattern. It could flip the script on how planets form, scientists say.

Astronomers have uncovered a distant planetary system that flips a long-standing rule of planet formation on its head. Around the small red dwarf star LHS 1903, scientists expected to find rocky ...

The planets around a nearby star seem to be in the wrong order, hinting that they formed through a different mechanism than the familiar one by which most systems grow ...

With this new survey, astronomers have gained a peek inside a stage of exoplanet system formation they have yet to fully ...

Astronomers have found a distant world that challenges planetary formation theory, with a rocky planet where gas giants should be.

Scientists have identified a rocky outer planet in a system where a gas giant was expected. The discovery challenges traditional models and supports the idea that planets may form one by one in ...