Friedrich Wilhelm Herschel, better
known as Sir William Herschel, was born in Hanover,
Germany on November 15, 1738.
Music was an important part of his
upbringing, this became evident when he became a bandboy
with the Hanoverian Guards. Later on he was either inducted
or a volunteer in the military where he served only
briefly. Due to his delicate health he discovered he
was unsuited for army life and his father helped him
to leave Germany for England in 1757 where he took up
residence. He was later reunited with his brother, Alexander,
and his sister Caroline who joined him in England.
His career in music began when he
was employed as a military bandmaster, then as a music
teacher and organist at the Octagon Chapel in Bath,
England. He also composed and gave concerts. He was,
in fact, a very successful musician. However, Herschel
developed an avid interest in astronomy and this became
his first love. He rented a small reflecting telescope,
but this only whetted his appetite to own his own, larger
telescope. Since he didn't have enough money to buy
one, he contrived to build it with the help of Alexander
and Caroline. This eventually led to the construction
of his largest telescope, a 48-inch reflector which
he build with a 4,000 pound grant from King George III.
However, most of his recorded observations were made
with his 20-foot reflecting telescope. Because of his
great zeal and methodical nature, William Herschel became
one of the most notable observers in the history of
astronomy. His systematic survey of the sky was one
of the most important of his accomplishments.
On March 13, 1781, while scanning the skies with a 7-inch
reflecting
telescope, he observed an unusual object; it presented
an extended disk-like shape. Herschel thought he had
discovered a comet. He continued his observations, and
calculations for months, discovering the orbit lay well
beyond the orbit of Saturn and was fairly circular.
Herschel's "Comet" was in fact a planet. Different names
were suggested, including his own name, "Herschel".
He, however, wanted to call the new planet "Georgium
Sidus," after his new patron, George III. This name,
however, did not find favor with the astronomical community.
It was eventually named Uranus after the mythological
god of the skies.
Herschel was granted a pension of
200 pounds a year and knighted by King George III, who
also made him "King's Astronomer". Receiving a pension
enabled Herschel to devote full time to astronomy.
The instruments Herschel had lacked
clock drives to keep them trained on the moving sky,
so the method he used was to direct his telescope to
a point on the meridian and watch what crossed the field
of view. Since Herschel had to stand on a ladder to
do his observing, he would call out descriptions of
whatever he saw of interest to his sister Caroline at
the foot of the ladder. She would then record the information
and time. By using this method he was able to observe
objects in a thin east-west strip of sky. As the nights
progressed, he would change the position of the telescope
to an elevation higher or lower than the previous night.
This enabled him to observe another strip of sky. They
eventually were able to observe all the sky visible
in Great Britain.
During the course of his observations,
he discovered large quantities of faint patches of light
(nebulae) and methodically catalogue these objects.
Herschel's son John took his father's instrument to
South Africa where he was able to survey the southern
skies. John Herschel in 1864 published a catalog. Of
the 5,097 objects, 4,630 of them were discovered by
William and his son John Herschel. The catalog was called
"The General Catalogue of Nebulae."
In 1888 this catalogue was revised
and enlarged by L.E. Dreyer. It now contained 7,840
nebulae and clusters. After its revision it was call
the "New General Catalogue". Most non-stellar objects
are still known by their new General Catalogue (NGC)
numbers.
Herschel's observations and discoveries
are numerous. He observed sunspots and confirmed the
gaseous nature of the sun. He discovered not only the
planet Uranus, but two of its moons, and also two of
Jupiter's moons.
His principal works were on stars.
Two discoveries of primary importance is the movement
of the solar system through space and the evidence that
binary stars move around a common center of gravity.
He discovered nearly 1,000 double stars.
In 1785 he brought out the disc theory
of the stellar system, anticipating the shape of our
own galaxy. Herschel believed that all nebulae are clusters
of stars which he called island nebulae.
He also discovered the infrared range
of sunlight. Sir William Herschel died in Slough, England
on August 25, 1822.
-Peggy Taylor & Sara Saey
Astronomical League National Headquarters
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