Earth’s atmosphere consumes most X-rays and gamma-rays. The more dynamic X-rays can enter the air for distances of at least a few meters, but the Earth’s atmosphere is dense enough that practically none are capable of entering from outer space. The first two origins of X radiation outside our galaxy was discovered in data collected by rocket-borne X-ray detectors. The new sources were then identified at the U.S. Naval Research Laboratory as corresponding with two of the most powerful radio-emitting galaxies, Cygnus A and M 87. Usually, to witness X-rays and gamma-rays from objects in space, we must put our telescopes and detectors above most of the Earth’s atmosphere. The three methods researchers do this are with rocket flights, scientific balloons, and satellites.
