Very Long Baseline Interferometry Is Developed for High-Resolution Astronomy and Geodesy (Great Events from History II: Science and Technology Series)
Article abstract: As an outgrowth of radio astronomy interferometry, Very Long Baseline Interferometry (VLBI) enabled the first high-resolution observations of distant radio galaxies, as well as new accuracy levels for global navigation.
Summary of Event
Radio telescopes, like their optical counterparts, gather electromagnetic energy at a spatial focus in order to measure intensity, frequency, spatial distribution, polarization, and variability of single or multiple radiating sources. As was established early in the post-World War II era, in order to make radio astronomy measurements with spatial resolution comparable to that at optical wavelengths, the radio receiver must be larger by the ratio of radio to optical wavelengths. This results from the fact that the angular resolution of a radio telescope is basically set by the ratio of the wavelength of the dominant radiation received (lambda) to the diameter of the total receiving instrument D.
Precisely establishing the location and characteristics of diffuse radio objects required antennas with well-known...
(The entire section is 2049 words.)
Want to Read More?
Subscribe now to read the rest of this article. Plus get complete access to 30,000+ study guides!
Very Long Baseline Interferometry Is Developed (Great Events: 1900-2001)
Article abstract: Very long baseline interferometry (VLBI) made it possible to study distant regions of the universe that had not been studied before.
Limits of the Radio Telescope
Astronomers have always wanted to study stars, planets, quasars, and other objects that are too far from Earth to be seen with conventional optical telescopes. Scientists discovered that they could learn about distant objects by studying the waves of radiation that those objects emit. They constructed radio telescopes, long dishlike apparatuses that faced up to the sky and that could collect incoming radiation waves. By studying those waves, astronomers could “see” into distant areas of the universe.
Radio astronomy, which uses radio telescopes to study objects and phenomena in the universe, was “discovered” by Karl Jansky in 1929. At that time, he was working at Bell Telephone Laboratories, studying a strange hiss that could be heard on telephone lines. Using the information he collected with a very crude radio telescope, he discovered that the hiss was caused by radio signals that came from the Milky Way.
After World War II ended in 1945, scientists built bigger and bigger radio telescopes. The largest radio telescope, which was built in Arecibo, Puerto Rico, had a 1,000-foot (300-meter) reflector dish to collect radio waves. Radio telescopes must be large because radio waves, which are a kind of radiation,...
(The entire section is 1033 words.)