Canadian-born US astrophysicist responsible for theories regarding the formation of the unstable element technetium within the core of red giant stars and of the disappearance of Earth's original atmosphere.

Cameron was born in Winnipeg, Manitoba, and educated at Manitoba and Saskatchewan. He emigrated to the USA 1959 and held successive posts at the California Institute of Technology; the Goddard Institute for Space Studies, New York; and Yeshiva University, New York. In 1973 he became professor of astronomy at Harvard.
Spectral lines denote the presence in red giants of technetium, an element too unstable to have existed for as long as the giants themselves. This means the element is created in the stellar core. Cameron suggested that technetium-97 (half-life 2.6 x 106 years) might result from the decay of a nucleus of molybdenum-97, a usually stable nuclide that becomes unstable when it absorbs an X-ray photon at high temperatures.
Cameron also suggested that the Earth's original atmosphere was blown off into space by the early solar 'gale' - as opposed to the present weak solar 'breeze' - with its associated magnetic fields.