ASTRONOMY: The VLA Telescope

13 Minutes

The Very Large Array, or VLA, telescope was built by the National Radio Astronomy Observatory to investigate radio waves from a variety of astronomical objects. This enormous array includes 27 antennas that look into deep space to see quasars, pulsars, remnants of supernova, gamma ray bursts, radio-emitting stars, the sun and planets, black holes, and the hydrogen gas that constitutes a large portion of the Milky Way galaxy. This episode takes a look at how the telescope works and some of the magnificent images it produces.

SYNOPSIS

Nowadays, there are many dierent types of telescopes astronomers use to study space. The most common include refracting, using lenses, and reecting, which use mirrors. There are also other types called radio telescopes which can detect all the radio waves that are part of the Electromagnetic Spectrum. These include not only infrared and ultraviolet light, but x-rays and gamma rays, as well. Radio telescopes make our understanding of the Universe better because many celestial objects such as pulsars or active galaxies (like quasars) are only “visible” because they produce large amounts of radio-frequency radiation. Radio telescopes function by means of a large parabolic dish which serves as the antenna. The best-known (and largest) radio telescope is in Arecibo, Puerto Rico. A well-known radio telescope that works with an array of antennae is the Very Large Array (VLA) in Socorro, New Mexico. The VLA was built in the 1970s by the National Radio Astronomy Observatory, but has gone through many updates in recent years to keep the instruments and technology up to date. The VLA is an instrument that has an array of 27 antennas that scientists use to investigate not only the sun and the planets, but also a variety of astronomical objects. These include radio galaxies, quasars, pulsars, remnants of supernova, gamma ray bursts, radio-emittng stars, black holes, and the hydrogen gas that constitutes a large portion of the Milky Way galaxy.

The Very Large Array, or VLA, is named after scientist Karl G. Jansky to honor his discovery of electromagnetic waves from the Milky Way. The VLA consists of 27 radio antennas in a Y-shaped configuration on the Plains of San Agustin, fifty miles west of Socorro, New Mexico. Astronomers use telescopes such as the VLA to accurately view celestial objects that give off different types of radiation. Some objects in space emit types of electromagnetic radiation from all over the spectrum, some of which cannot be seen by the human eye, such as radio waves.

We are limited in observing the world around us because our eyes can only detect one type of electromagnetic radiation, visible light. The full range of all radiating waves in the electromagnetic spectrum includes everything from gamma rays, high frequency with short wavelength, to radio waves with low frequency and long wavelength.

Because radio waves penetrate dust, astronomers use radio astronomy techniques to study regions that cannot be seen in visible light, such as the dust-shrouded center of our Galaxy, the Milky Way. Studying radio waves, they are capable of tracing the location, density, and motion of the hydrogen gas that constitutes three-fourths of the ordinary matter in the Universe.

VOCABULARY

Aperture synthesis: An array of radio telescopes used in radio astronomy to simulate a single large-aperture telescope. Some such instruments use movable dishes while others use fixed dishes.
Electromagnetic spectrum: The entire range of electromagnetic radiation. At one end of the spectrum are gamma rays, which have the shortest wavelengths and high frequencies. At the other end are radio waves, which have the longest wavelengths and low frequencies. Visible light is near the center of the spectrum.
Gamma ray bursts: A short-lived, extremely luminous burst of gamma radiation from an unknown astronomical source, occurring at random positions in the sky several times a day.
Pulsars: One of several hundred known celestial objects, generally believed to be rapidly rotating neutron stars that emit pulses of radiation, especially radio waves, with a high degree of regularity.
Quasars: One of over a thousand known extragalactic objects, star-like in appearance and having spectra with characteristically large redshifts, that are thought to be the most distant and most luminous objects in the universe.
Radio waves: A very low frequency electromagnetic wave (from roughly 30 kilohertz to 100 gigahertz). Radio waves are used for the transmission of radio and television signals; the microwaves used in radar and microwave ovens are also radio waves. Many celestial objects, such as pulsars, emit radio waves.
Super-massive black hole: The largest type of black hole, formed at the beginning of the universe or by the gravitational collapse of a star exploding as a supernova, whose gravitational field is so intense that no electromagnetic radiation can escape.
The Very Large Array: A set of 27 radio telescopes arranged in a Y -shaped pattern, each arm of which is approximately
13 miles (21 km) long, and located near Socorro, N.M. The largest type of black hole, formed at the beginning of the universe or by the gravitational collapse of a star exploding as a supernova, whose gravitational field is so intense that no electromagnetic radiation can escape.
The Very Large Array: A set of 27 radio telescopes arranged in a Y -shaped pattern, each arm of which is approximately
13 miles (21 km) long, and located near Socorro, N.M.

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CURRICULUM UNITS

  • EARTH AND SPACE SCIENCE
  • PHYSICAL SCIENCE

CAREER POSSIBILITIES

  • ASTRONOMER
  • ASTROPHYSICIST

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