We know it’s out there, but experts don’t know what makes up the invisible dark matter that accounts for most of our universe.
New images of the Sculptor dwarf galaxy bring lessons about the Milky Way
Hubble Space Telescope faces an uncertain future as it approaches its 25th birthday
Astrophysicist Charles Hailey is building instruments to examine dark matter, black holes and more
This year’s physics winners find the universe is accelerating