Maunder, Edward Walter (1851–1928)
English astronomer who, after working briefly in a bank, became photographic
and spectroscopic assistant at the Royal
Greenwich Observatory in 1873. Maunder's appointment allowed Greenwich
to branch out from purely positional work, for Maunder began a careful study
of the Sun, mainly of sunspots and related
phenomena. After 1891 he was assisted by his second wife, Annie Scott Dill
Maunder, neé Russell (1858–1947), a Cambridge-trained mathematician.
It had been known since 1843 that the intensity of sunspot activity went
through an 11-year cycle. In 1893 Maunder, while checking the solar
cycle in the past, came across the surprising fact that between 1645
and 1715 there was virtually no sunspot activity at all. For 32 years not
a single sunspot was seen on the Sun, and in the whole period fewer sunspots
were observed than have occurred in an average year since. He wrote papers
on his discovery in 1894 and 1922 but they aroused no interest. (Gustav
Spörer reached the same conclusion as Maunder
even earlier.) More sophisticated techniques developed in recent years have
established that Maunder was correct in the detection of was has become
known as the Maunder minimum. The realization that the
period of the minimum corresponds to a prolonged cold spell suggests that
Maunder's discovery is no mere statistical freak. It may throw light on
the Sun's part in long-term climatic change and on possible variations in
the processes within the Sun that produce the sunspots.
Maunder also played a significant part in the debate on the canals
of Mars by carrying out experiments with marked circular disks and concluding,
as did Simon Newcomb, that the canals "are
simply the integration by the eye of minute details too small to be separately
and distinctly defined."
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