Scientists detected the gravitational waves after a pair of unusual black holes collided.
More than two weeks after that attack on the gas refinery in Algeria, questions remain about how a group of Islamist militants was able to infiltrate the plant.
The site, run by BP and the Algerian national gas company, is heavily guarded and there’s an Algerian army base nearby.
Eventually, the Algerian government decided to storm the complex but in the end nearly 50 hostages were killed.
The BBC’s Richard Galpin is one of the first Western journalists to visit the Amenas refinery since the hostage crisis.
Robin Young and Jeremy Hobson are hitting the road. Our Tumblr brings you behind the scenes of our election coverage.