Green Bank - Part 1
For a second time this school year, my Glenville
State College classmates and I took a trip to the National Radio
Astronomy Observatory in Green Bank.
Last November, we studied the Milky Way Galaxy.
When you look at the night sky, you can see many
visible objects, because they reflect or emit light. What you don’t see
is the other kinds of waves that are also emitted by the universe, such
as radio waves, microwaves, infrared radiation, ultraviolet light,
X-rays, and gamma rays. We can only observe visible light and radio
waves from Earth, because the atmosphere absorbs the other waves. To
observe radio waves, a radio telescope must be used.
When radio waves are emitted by celestial objects
toward the Earth, the waves travel through the Earth’s atmosphere. If
you could turn your radio to 1420.4, you would be able to hear the
hydrogen radio waves sent from the galaxy. Since your car radio isn’t
able to pick up these frequencies, and just listening would not provide
useful information, astronomers use radio telescopes to collect data.
Astronomers process this data to make sense of it.
Radio telescopes can be vastly different, but two
parts are a constant throughout all radio telescopes: a large radio
antenna and a radio receiver. How well a radio telescope can measure the
source of a radio emission depends on the area of the antenna and the
amplification of the radio receiver. Because cosmic radio sources are so
weak, radio telescopes are usually very large and use only the most
sensitive radio receivers available.
The most familiar type of radio telescope is one
that looks similar to a television satellite dish antenna. They operate
in the same way, by focusing the incoming wave onto a small antenna,
called the feed. If you have a satellite dish, the feed is the part that
is suspended above the dish. In a radio telescope, the feed transfers
the incoming signal to the radio receiver.
National Radio Astronomy Observatory operates the
world’s largest radio telescope (328 ft diameter) in Green Bank. The
observatory contains many other telescopes of varying diameters,
including one 140-ft. telescope, three 85-ft. telescopes, and a 40-ft.
telescope. The 40-ft. telescope is an educational instrument for small
scale research, used by teachers and students ranging from fifth grade
to graduate students.
(Continued Next Week)