William [Wilhelm Friedrich] Herschel was born on 15 November 1738 in
Hanover, in a family of musicians. In 1757, at age 19, he fled to England.
With his
name anglicized to William, Herschel began earning a living as an organist
and later composer and conductor. In
1772 convinced his sister Caroline to join him
as an accompanying singer. In their spare time the brother-sister team
became engaged in astronomy, in particular in the building of
ever greater size and magnifying power.
William died at his home in Slough, near Windsor, on August 25 1822,
and Caroline on September 1 1848.
Herschel's first major
discoveries were to show that Mars and Jupiter exhibit axial
rotation.
Herschel struck fame in 1781, when on March 13 he discovered
the planet Uranus while engaged in work aimed at determining
stellar parallax. This being the first new planet discovered
since Antiquity, Herschel, until then a mere amateur astronomer
relatively unknown even in England, became a celebrity.
Adopting an historically proven strategy, Herschel named the new
planet Georgium Sidum, in honor of the then ruling English
monarch George III. The trick worked once again, as King George III
gave William and Caroline the titles of "The King's Astronomer"
and "Assistant to the King's Astronomer", an honor which came
with a life's pension for both.
In 1782 they moved to Bath, and shortly thereafter to
Slough, near Windsor,
and from this point on William and
Caroline could devote themselves entirely to astronomy.
The Heschels went on to discover two moons of Uranus in 1787,
and two new moons of Saturn.
Herschel's work on double stars, which he pursued intermittently
between 1782 and 1821, provided the first demonstration that gravity
acted also outside the solar system.
He also made one of the first attempts at
measuring the
Sun's motion through the galaxy via the proper motion of nearby stars.
This became yet
another step in the removal from the Earth as the center of
the Universe. His increasingly large and powerful telescopes also
allowed him to resolve many of the hitherto mysterious "nebulae"
into clusters of faint stars. Anticipating in some ways
Laplace's model for the formation
of the solar system, Herschel developed an evolutionary theory of the universe,
where, starting from a uniform "initial state", stars form and clump
into nebulae.
While Caroline became increasingly occuppied with the
search for comets (at which she was quite successful),
William became for a time interested in the Sun. Inspired by
Wilson's 1774 work, he put forth the theory of
sunspots as openings in the Sun's luminous atmosphere,
an opinion that was to endure well into the nineteenth
century. In 1800 he became interested in the solar spectrum,
and uncovered the first evidence for
solar energy output
outside of the visible spectrum, in what is now known as
the infrared.
In 1801 he published two papers that, in part because of
Herschel's reputation, effectively launched the field of solar
influences on Earth's weather. It is in the first of
these papers that Herschel discusses an anticorrelation between
the price of wheat and the number of sunspots visible on
the Sun.
Bibliography:
Herschel, W. 1801, in Philosphical Transactions of the Royal Society,
London, 265 and 354.
Sidgwick, J.B. 1953, William Herschel. Explorer of the Heavens,
Faber & Faber, London.
Hoskin, M.A. 1963,
William Herschel and the construction of the heavens,
Oldbourne, London.
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