China’s Micius satellite, launched in August last year, has been used to distribute quantum entanglement over a distance of 1200 km – beating previous terrestrial records by an order of magnitude. Juan Yin of the University of Science and Technology and co-workers used a 405 nm laser to pump a periodically poled KTiOPO4 crystal inside a Sagnac interferometer on board the satellite, producing two entangled down-converted photons with a wavelength of about 810 nm. These were then sent to separate receiving stations in Delingha and Lijian located 1200 km apart in the Tibetan mountains. The team observed the survival of two-photon entanglement and measured a violation of Bell’s inequality by a factor 2.37±0.09 under Einstein locality conditions. Until now, free-space demonstrations of entanglement have been limited to line-of-sight links across cities or between mountaintops, with link separations limited to around 100 km due to scattering and coherence decay. The new result therefore marks a big advance for secure communications networks and, in the future, a space-based quantum internet.