Ultra-high-energy gamma rays are stopped by the Earth’s atmosphere before they can reach the planet’s surface. However, our atmosphere could also become a tool for detecting photons with energies in the teraelectronvolt range. By using instruments registering Cherenkov radiation, astronomers conduct observations of sources emitting ultra-high-energy photons with ground-based telescopes.
The Long March-2F rocket was launched on 15 September 2016 from the Jiuquan Satellite Launch Centre in China, carrying the Tiangong-2 space laboratory. The laboratory is fitted with the detector of the POLAR experiment, which was prepared jointly with Polish scientists.