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 June
22 , 2004 — As
Alan learned from Max Tegmark and Chuck Bennet in the segment
"In the Beginning,"
equipment such as the WMAP is capable of capturing the first
light of the Universe. The WMAP detects invisible cosmic microwave
background radiation -- the faint afterglow of the Big Bang.
Before
the 1600s astronomers studied the cosmos with thier naked
eyes. Today we use sophisticated, computer-driven telescopes
and satellites -- such as the WMAP -- to do our looking for
us. Learn more about these eyes into the skies.
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Humble
Beginnings
In the early 1600s, as children played outside the Dutch spectacle
maker Hans Lippershey's place of business, an important astronomer's
tool was conceived. The children were fooling around with
some of his lenses. When they were arranged just so -- about
a foot apart -- the birds nesting in the spire of the local
church steeple appeared much closer than they really were.
News
of this discovery spread across Europe to the mathematician
Galileo at the University of Padua in Italy. He seized upon
this newfound technology, becoming the first person to see
the craters of the moon, discover sunspots, the four large
moons of Jupiter, and the rings of Saturn. Compared to today's
telescopes, Galileo's tool was unrefined, providing limited
magnification -- up to 30 times -- and a narrow field of view.
Galileo could see no more than a quarter of the moon's face
without repositioning his telescope.
The
basic refracting telescope is a two-step device. First a glass
lens gathers light from a distant source and refracts or bends
the light to focus on a single spot. Then an eyepiece lens
magnifies that focused light into an enhanced image of the
celestial body.
Because
a telescope's ability to magnify depends on how much light
it can gather, astronomers made bigger lenses which in turn
gathered more light. Unfortunately, once a glass lens is bigger
than three feet across it starts to sag in the middle, thus
distorting its shape and negatively affecting its light-collecting
abilities.
In
the 1700s, Newton made a huge innovation in telescopes. He
incorporated mirrors as opposed to glass lenses. As opposed
to glass, mirrors could be supported from behind without affecting
the reflective properties of the surface. This allowed for
them to get bigger but still maintain their integrity without
losing their shape to the forces of gravity. Telescopes -
or "light buckets," as astronomers refer to them - incorporated
larger and larger mirrors to collect more and more photons.
As these mirrors grew bigger, two things happened: astronomers
were able to see fainter, more distant stars and they were
able to see them more clearly, with better resolution.
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