A monster merger between two black holes sent ripples through time and space, and may prove Einstein right about a gravitational phenomenon called precession.
Earth’s highest, coldest, rarest clouds are back. How to see the eerie ‘noctilucent clouds’ this summer.
Look North as the stars appear in June and July to have a chance of seeing rare noctilucent (or ‘night-shining’) clouds with the naked eye.