One of the most vexing gets at the heart of what our universe is actually made of. Cosmological observations have determined the average density of matter in our universe to very high precision. But this density turns out to be much greater than can be accounted for with ordinary atoms.
Captured using the exceptional sky-surveying abilities of the VLT Survey Telescope (VST) at ESO's Paranal Observatory in Chile, this deep view reveals the secrets of the luminous members of the Fornax Cluster, one of the richest and closest galaxy clusters to the Milky Way.
For three decades, astronomers thought that only Saturn's moon Janus confined the planet's A ring -- the largest and farthest of the visible rings. But after poring over NASA's Cassini mission data, astronomers now conclude that the teamwork of seven moons keeps this ring corralled.
NASA's Juno spacecraft has helped explain how volcanoes on the moon Io spew particles that are flung out by Jupiter's magnetic field, before rebounding back. A high-speed atmospheric encounter on the return leg creates the Red Giant's once mysterious transient auroras.