Space.com

What's Hot This Week What's 96 Percent of the Universe Made Of? Astronomers Don't Know By Clara Moskowitz All the stars, planets and galaxies that can be seen today make up just 4 percent of the universe. The other 96 percent is made of stuff astronomers can't see, detect or even comprehend. Superflare from Crab Nebula Has Astronomers Mystified By SPACE.com Staff The Crab Nebula, the dusty remains of an exploded star, has unleashed a surprisingly massive flare that is five times more powerful than any eruption previously seen from the celestial object, leaving scientists struggling to explain the event, NASA says. Sponsored by: Weird Alien Planets Stuck in Backwards Orbits Explained Gallery: President Obama and NASA Dying Stars to Collide and Create Stellar Baby How China's First Space Station Will Work (Infographic) Photos: STS-134: Shuttle Endeavour's Final Voyage