Scientists have revealed that the number of observed exoplanets - worlds circling distant stars - has passed 1,000.
Voyager 1 has become the first spacecraft to leave our neighbourhood and venture into the loneliness of interstellar space, according to data published on Thursday.
A new type of atomic clock may be a more accurate way to measure time, scientists say.
Venus is spinning on its axis so slowly that, for any survivor, a day in Venus would seem interminable, as it is the equivalent of 243 days on Earth, researchers say.
Day in Pics: 21st December
Showbiz World - December 21, 2014
People Magazine Awards 2014