Travel through galaxies and the dark matter web in this stunning universe simulation

Largest virtual universe free for anyone to explore

Astronomers spot the same supernova 3x—and predict a 4th sighting in 16 years. An enormous amount of gravity from a cluster of distant galaxies causes space to curve so much that this "gravitational lensing" effect has astronomers to observe the same exploding star in three different places.

A supernova’s delayed reappearance could pin down how fast the universe expands