Astronomy is a unique field of science in which amateur astronomers have made and continue to make significant contributions.

One major area of the science of astronomy is the study of variable stars. There are more than 28,000 known and catalogued stars that change in brightness – variable stars – and about 15,000 suspected to be variable. These stars need continuous and systematic observing over decades to determine their behaviour and to record any of their unusual or rare activity. However, there are not enough professional astronomers or telescopes to observe these stars regularly. Therefore, variable star astronomy needs amateur astronomers to be the record keepers for these stars. It was for this reason that as early as 1844 and continuing throughout the second half of the nineteenth and early twentieth centuries, the astronomers F.W. Argelander of Germany, Sir John Herschel and J. Baxendell of England, D.F.J. Arago of France, and E.C. Pickering of the United States all advocated systematic variable star observing for amateur astronomers. The encouraging appeals from these leading professional astronomers resulted in the formation of several organized groups of variable stars observers, first in England – the British Astronomical Association (1890), Variable Star Section; then followed by the American Association of Variable Star Observers (1911); the Association Française des Observateurs d’Etoiles Variables (1921); the Royal Astronomical Society of New Zealand, Variable Star Section (1927); and the Japanese Astronomical Study Association (1945). Today, there are about 25 variable star observer groups around the world.