Proxima Centauri, the closest star to our sun, may have a second planet, according to researchers from the National Institute of Astrophysics. If confirmed, it would be an ideal candidate for direct imaging by new upcoming space telescopes.

Why isn't there an endless variety of planet sizes in the universe? Why are most planets like those in our solar system: small and rocky, or big and gaseous? 

New laboratory studies - simulating conditions on the planet Mars and using salt-loving microbes - suggest that similar organisms could be producing Mars' mysterious methane.

Watch the last of January's 3 International Space Station spacewalks tomorrow.

A new research study suggests that K-type dwarf stars (smaller and cooler than our sun) are the best place to search for alien life. These stars are not too hot, not too cool, and not too violent for life to evolve.

Cast your vote to help name the next Mars rover, scheduled to launch in July or August 2020. The names were drawn from 9 finalist essays written by K-12 students. The voting will remain open through January 27.

For future homes on the moon, Mars, and other worlds, NASA is exploring technologies that would use mushrooms to grow self-repairing, self-replicating habitats.

Grains of stardust - particles left behind by star explosions - in an Australian meteorite are now the oldest known material on Earth. A new study suggests this stardust came to be long before our sun ever existed.

The Gaia-Enceladus dwarf galaxy slammed into our Milky Way 11.5 billion years ago. It added the mass of 50 billion suns to the Milky Way. Grand names and big numbers! Now new knowledge of this collision comes from a single bright star visible in Southern Hemisphere skies.

Hyperbolic comets fly through our solar system at high speed before heading out to interstellar space, never to return. A new study from astronomers in Japan identifies 2 hyperbolic comets that likely originated outside our solar system.