October 6, 2000

How was the first radio telescope developed?

A radio telescope is a highly directional radio antenna that is able
to create a map of the sky by recording signals coming from different
directions. Although radio engineer Karl Jansky was the first to
identify deep space radio signals in 1931, his antenna was not good
at pinpointing individual sources.

The first steerable radio telescope was built in 1937 by Grote Reber,
who had applied to work with Jansky but was turned down because of
the poor economic times. So he decided to build his own radio
telescope, a 31.4-foot metal dish (9.6 meters) mounted on a
directional cradle in Wheaton, Illinois.

With his radio telescope, Reber was able to detect radio emissions
from the Sun, the center of the Milky Way Galaxy, and several
other "radio-bright" sources. By 1941, he had completed the first
crude radio survey of the northern sky. Today his radio telescope is
an historical monument in Green Bank, West Virginia.

Grote Reber and his radio telescope:
http://www.gb.nrao.edu/~fghigo/fgdocs/reber/greber.html

All about natural radio signals:
http://www.altair.org/natradio.htm

Jansky's original antenna:
http://features.LearningKingdom.com/fact/archive/1998/10/01.html