Looking back: The Sky at Night
June 1977
On the 28 June 1977 episode of The Sky at Night, Patrick Moore spoke with astrophysicist Jocelyn Bell Burnell about the rapidly expanding field of gamma-ray astronomy.
Gamma rays are high energy photons created by equally energetic events. For the first half of the 20th century, astronomers theorised that violent events such as supernovae could produce gamma rays. However, Earth’s atmosphere does a good job of absorbing such radiation, making it difficult to observe the rays from the ground.
By the early 1960s, astronomers were finally able to put gamma-ray detecting satellites into orbit, where they could detect the rays. The first was NASA’s Explorer 11, which picked up 100 photons coming from all over the Universe, suggesting some kind of gammaray background. The most surprising discovery came in the late 1960s, when a set of military satellites designed to detect the gamma emissions of nuclear bombs detected flashes of gamma rays lasting from a few seconds to a few minutes coming from deep space. These bursts have since been tracked back to distant galaxies and are thought to come from the highly energetic supernovae.