Saturn captured by the Cassini probe, NASA.

At 4 billion light-years in length, the Large Quasar Group (LQG) is the largest known structure in the universe and is some 1600 times larger than the distance from the Milky Way to Andromeda.

These are the latest images of Gigi Crater taken by NASA's Mass Reconnaissance Orbiter. courtesy NASA

For more than 100 years, Curie's clothing, furniture, books, and laboratory notes have been radioactive. Curie's laboratory notebooks are still housed in lead - lined boxes in museums in France. Marie Curie's goods will still be radioactive for 1500 years.