Victoria Billings age 14: of Portland ore  for her question

HOW DOES A RADIO TELESCOPE WORK?

A radio telescope is an instrument that collects and measures faint radio waves given off by objects in space For the radio telescope to work, most must have a parabolic or bowl shaped reflector to collect radio waves from space

A radio telescope reflector is made from wires or metal sheets Motors in a telescope can turn the reflector toward any source of radio waves in the sky The reflector then focuses these waves on a small radio antenna. which changes them into an electronic signal

A radio receiver takes the signals from the antenna and tunes in only the signals that the astronomer wishes to observe.

The receiver amplifies or strengthens the signals and then records them. The signals may be recorded as wavy lines on paper or on a tape that can be analyzed by an electronic computer. The computer combines the signals from the receiver and uses them to draw a picture of the source of the radio waves.

Two or more radio telescopes can be connected to produce a sharper radio picture of an object than a single telescope can Astronomers use the term "radio interferometer" for telescopes connected in this way. The longer the base line or distance between the telescopes. the better the interferometer can focus on an object

Astronomers can make a very long base line interferometer, sometimes using telescopes located on different continents Both telescopes observe the same object and record the radio signals from it on a computer tape A computer later plays the tapes from each telescope and compares the signals In this way, astronomers can produce pictures of radio sources that are about 1 000 times as sharp as images produced by light telescopes

Many radio telescopes can also send powerful radio waves to the moon and to the planets nearest the earth. The telescope then picks up the radio echoes coming back

Astronomers call the techniques of sending powerful radio waves to the moon and to planets "radar astronomy" because it operates on the same principle as radar By studying the radio echoes, they can measure the distance to the moon or planet.

Astronomers can also use the echoes to make a map of the moon or planet that shows details as small as 300 yards wide.

An American engineer named Karl Jansky accidentally discovered radio waves from space in 1931 In 1939, an American amateur radio operator named Grote Reber built the first radio telescope

After World War II ended in 1945, astronomers in Australia, England and the Netherlands experimented with radio astronomy.

In 1957. the British astronomer Sir Bernard Lovell built the first giant radio telescope The reflector of this telescope. at the Jodrell Bank Observatory in Manchester England, has a diameter of 250 feet

The world s largest radio telescope, with a reflector 1.000 feet in diameter, is located near Arecibo Puerto Rico.