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PHOTOGRAPHING
THE STARS
ASTROPHOTOGRAPHY
IN CONTEXT
KEY ASTRONOMER
David Gill (1843–1914)BEFORE
1840 The first clear
photograph of the moon
is taken by American
John Draper, using a
20-minute exposure.1880 John Draper’s son
Henry takes a 51-minute
exposure of the Orion
nebula. He also takes the
first wide-angle photograph
of the tail of a comet.AFTER
1930 US astronomer
Clyde Tombaugh discovers
Pluto by spotting a moving
object on photographic plates.1970s Charge-coupled
devices replace photographic
plates and film with digital
photographs.1998 The Sloan Digital
Sky Survey begins to make
a 3-D map of galaxies.I
saac Newton’s theory
of gravitation, like many
advances of the Scientific
Revolution (pp.42–43), was based
on a belief that the universe
worked like clockwork. In the
1880s, David Gill, a master
clockmaker from Aberdeen,
Scotland, applied his precision
clockmaking machinery to
astronomical telescopes—and,
ironically enough, offered a way
of showing that the stars were
not all moving in clocklike unison.Accurate maps
reveal that stars are
moving at different
speeds and in
different directions.However, Earth’s
rotation makes images
blurry. A precise
tracking mechanism
is needed to move
the camera.Photographs of the
stars can be used to
make very accurate
star maps.Gill was a pioneer in the field of
astrophotography. In the mid-1860s,
then still an amateur astronomer
working in his father’s backyard,
he built a tracking mount for his
12-in (30-cm) reflecting telescope,
and used it to photograph the
moon with a clarity that had never
been seen before. The photographs
earned Gill a fellowship in the
Royal Astronomical Society,
and, by 1872, his first job as a
professional astronomer at the
Dunecht Observatory in Aberdeen.Photographing
the stars requires
long exposures.