Scientists speculate that ours might not be the only universe out there — we might instead live in a "multiverse".
UFOs, or Unidentified Flying Objects, and extraterrestrials are perennial favorites in science fiction, but to date there have been no confirmed encounters on Earth.
NASA is the federal space agency run by the United States to oversee American space exploration, research and technology.
Meteors, also known as shooting stars, are pieces of dust and debris from space that burn up in Earth's atmosphere, where they can create a bright streak across the night sky.
Gravitational waves are ripples in space-time created by the interaction of massive objects in space, such as black holes and neutron stars.
The International Space Station is a $100 billion research outpost in low-Earth orbit. See the latest news, photos and videos from ISS missions here.
Rocket launches used to be the realm of national governments, but with the rise of private spaceflight companies more rockets are launching into space than ever before.
NASA's Jupiter-bound Juno probe will study the gas giant's atmosphere, magnetosphere and gravitational field. Juno will orbit Jupiter for about a year.
The aurora borealis, also known as the northern lights, is the rippling night-sky light display found at the northernmost reaches of the Earth.
Roughly 80 percent of the mass of the universe appears to be dark matter: a material that seems to interact with ordinary matter only through gravity, without emitting light or energy.
Learn more about SpaceX's Falcon Heavy rocket, the world's most powerful booster, which made its debut flight on Feb. 6, 2018.