Because their energy is strongly beamed (very narrow), the gamma rays emitted by most bursts miss the Earth and are never detected. When a gamma-ray burst is pointed towards Earth, the focusing of its energy along a relatively narrow beam causes the burst to appear much brighter than it would have been were its energy emitted spherically. When this effect is taken into account, typical gamma-ray bursts are observed to have a true energy release of about 10 J, or about 1/2000 of a Solar mass energy equivalent.