- How Large are Radio Waves? Of all types of light, radio waves have the longest wavelengths. Radio waves are longer than 1 mm
and can be very long.
- In fact, the most common radio emission in the galaxy is at 21
cm, (about the length of the average forearm). This radiation is produced by hydrogen
- Astronomers use the 21 cm radio radiation to probe the gas and
dust located between stars.
- Good Sources of Radio Waves: Hydrogen atoms, like we mentioned, are good sources of radio waves. Other
sources of radio emission are from stars like our Sun. Distant galaxies or quasars
(luminous objects at the center of some galaxies) can also be bright radio sources.
- Radio telescopes have to be large in order to capture these long
waves. Scientists and engineers sometimes build several dishes that they hook up
together to capture or record radio waves with more detail than single dishes can
provide. These are called "arrays."
- The Very Large Array located in Socorro, New Mexico is
one of the world's premiere astronomical radio observatories. The VLA consists of
27 antennas arranged in a huge Y pattern up to 36km (22 miles) across -- roughly
one and a half times the size of Washington, D.C.