His new
design allowed William Herschel to build the largest telescope
of the day, a record maintained for over 50 years. Unfortunately,
the Herschels didn't use this telescope regularly, since the necessary
giant structure was awkward and difficult to use. Using their
homemade telescopes, the Herschels studied the solar system thoroughly
and successfully, studying sunspots, discovering numerous comets
and additional moons of Saturn and Uranus. Their gaze also went
beyond our sun’s immediate neighborhood, and the stars in
our milky way came into focus. Realizing that the Milky Way appears
to be approximately equally faint across the sky, William Herschel
induced that the Sun must be close to the center of our galaxy.
On
this matter he was wrong, and later generations of astronomers
assisted by better instruments would correct him. In any
case, William Herschel must receive credit for being one
of the first to systematically study our Milky Way Galaxy,
and to postulate theories about its shape based on his
observations.
In one other important respect, William Herschel broke
new ground for future astronomers: He was the first to
report about infrared radiation from a star, our own sun.
When sending sunlight through a prism, thus breaking them
down into their primary colors, William Herschel could
measure an increase in temperature just beyond the red
portion of the light spectrum. He concluded that the sun
must give off rays that are not visible but transport
heat nonetheless. Today these rays are called ‘infrared
light’. Thus the European Space Agency decided to
use William Herschel’s name for their infrared space
observatory. He was the first astronomer to view an object
in the sky in the infrared, and due to the Herschel mission,
many astronomers will be able to follow in his footsteps.
