BBC News looks back on eight of the biggest science and environment stories of 2017. Star crashArtist's impression of two neutron stars colliding -- Photo: PAIn 2017, scientists detected Einstein's gravitational waves from a new source - the collision of two dead stars, or neutron stars. Some of the facts about these cataclysmic events are staggering: for example, neutron stars are so dense that a teaspoonful would weigh a billion tonnes. The findings suggested that far from being an ancestor of present-day people, Homo naledi may even have encountered very early members of our own species - Homo sapiens. Discovered by a team using Hawaii's Pan-Starrs telescope in October, they were soon sure that the object's speed and trajectory indicated an origin outside our Solar System.

Source: VietNamNet News December 25, 2017 09:37 UTC