Astronomers are closing in on one of the most tantalizing possibilities in planetary science, evidence that a previously unknown world may be lurking in the outer reaches of the solar system. The ...

Remember 3I/ATLAS? Yes, the interstellar comet that made plenty of headlines in 2025 is still romping through our solar system.

Planetary systems such as our solar system take hundreds of millions of years to evolve. Since humanity has only existed for a sliver of that time, astronomers have only observed planetary systems at ...