Test your knowledge on our solar system, from the biggest and smallest planets to the behemoth mountain on Mars. When you purchase through links on our site, we may earn an affiliate commission.

"It is possible that a planet once existed in the solar system but was later ejected, causing the unusual orbits we see today." When you purchase through links on our site, we may earn an affiliate ...

The comet 3I/ATLAS moves against a backdrop of stars. The ATLAS survey telescope in Rio Hurtado, Chile, was the first to report that the object came from interstellar space. ATLAS / University of ...

SETI Institute communications specialist Beth Johnson welcomed Professor Dagomar Degroot, environmental historian at Georgetown University, for a discussion on his new book Ripples on the Cosmic Ocean ...

The three missions launched on a SpaceX Falcon 9 rocket the morning of September 24. NASA A SpaceX launch early Wednesday morning sent a trio of spacecraft toward a destination almost one million ...