Cosmology

Astronomers estimate 4.5 billion Earth-like planets are spread throughout the Galaxy

Maintenance, improvement work and data analysis will keep scientists busy as the European collider's planned closure begins

Microscopic analyses of chondrites, the oldest rocks in the solar system, are filling in details of what our neighborhood in space was like shortly before the planets formed

The solar system's moons may have emerged from long-gone planetary baubles

Scientific American contributing editor George Musser answers viewer questions submitted to YouTube's Spacelab Channel

The Relativistic Heavy Ion Collider is first in line for possible budget cutbacks

Science has progressed from wild ­speculation about Earth's planetary neighbors—including how they formed and whether they are inhabited—to a better ­understanding of our celestial neighborhood

The proximity of HD 140283, at 186 light-years from our solar system, made it a target of a highly precise age measurement that put it at 13.2 billion years old

New calculations extend Einstein's general theory of relativity into the universe's first few moments

If a new hypothesis about black hole firewalls proves correct, at least one of three cherished notions in theoretical physics must be wrong.

The latest finds from Hubble date to just a few hundred million years after the big bang

The Geminid Meteor Shower offers stargazers a host of slow, bright fireballs and lasts for two to three days