![X-ray data from NASA's Fermi, RXTE, and Swift satellites and the European Space Agency's International Gamma-Ray Astrophysics Laboratory (INTEGRAL) confirm that the Crab Nebula's output has declined about 7 percent in two years at energies from 15,000 to 50,000 electron volts. They also show that the Crab has brightened or faded by as much as 3.5 percent a year since 1999. Fermi's Large Area Telescope (LAT) has detected powerful gamma-ray flares (magenta lines) as well.](/6861089/original-1517424048.jpg?t=eyJ3aWR0aCI6MjQ2LCJvYmpfaWQiOjY4NjEwODl9--14cabd8354041a00894ac43030c8a2248e7ad462)
X-ray data from NASA's Fermi, RXTE, and Swift satellites and the European Space Agency's International Gamma-Ray Astrophysics Laboratory (INTEGRAL) confirm that the Crab Nebula's output has declined about 7 percent in two years at energies from 15,000 to 50,000 electron volts. They also show that the Crab has brightened or faded by as much as 3.5 percent a year since 1999. Fermi's Large Area Telescope (LAT) has detected powerful gamma-ray flares (magenta lines) as well.
Image credit: NASA's Goddard Space Flight Center
![While Fermi flew over Egypt, the GBM intercepted a particle beam from a terrestrial gamma-ray flash (TGF) that occurred in a thunderstorm below its horizon.](/6861291/original-1517424053.jpg?t=eyJ3aWR0aCI6MjQ2LCJvYmpfaWQiOjY4NjEyOTF9--157067c169d7c1dd5f6990b7250b9b16aec7ed16)
While Fermi flew over Egypt, the GBM intercepted a particle beam from a terrestrial gamma-ray flash (TGF) that occurred in a thunderstorm below its horizon.
Credit: NASA/Goddard Space Flight Center