All light waves behave like cosmic messengers.They race across space, bearing precious bits of information about the objects that radiated them. Telescopes detect the light, extract the data and transmit it to waiting scientists for analysis and understanding. 

Radio frequencies of light are part of the electromagnetic spectrum, just as are the wavelengths of visible light our eyes can see. That means that objects in space that give off radio emissions are undergoing exciting and energetic processes.

The science of radio astronomy is the study of celestial objects that are not always visible to us. They are hidden from our view until we aim radio telescopes in their direction. Radio astronomy reveals an unseen universe we cannot detect with our eyes. Light from the radio portion of the electromagnetic spectrum is the most common radiation given off by celestial objects. Ever since the first radio telescopes were built in the late 1920s by Bell Labs physicist Karl Jansky, astronomers have used them to expand our view of the universe.

There are radio telescopes around the planet, each tuned to frequencies in the radio band that come from naturally emitting objects in space. One of the most famous radio astronomy observatories is the Karl G. Jansky Very Large Array (VLA), located near Socorro, New Mexico, which is part of the United States. It is a collection of 27 radio telescope dishes arranged in a Y-shaped pattern. Each antenna is large — 25 meters (82 feet) across. The observatory welcomes tourists and provides background information about how the telescopes are used.

Many people are familiar with the array from the movie Contact, starring Jodie Foster.

The VLA is now also known as the EVLA (expanded VLA), with upgrades to its electronics, data handling, and other infrastructure. In the future it may get additional dishes. 

The VLA's antennas can be used individually, or they can be hooked together to create a virtual radio telescope up to 36 kilometers wide! That allows the VLA to focus in on some very small areas of sky to gather details about such events and objects as stars turning on, dying in supernova and hypernova explosions, structures inside giant clouds of gas and dust (where stars might be forming), and the action of the black hole at the center of the Milky Way Galaxy. The VLA has also been used to detect molecules in space, some of them precursors to pre-biotic (related to life) molecules common here on Earth. 

The radio waves detected by the VLA have often traveled across immense stretches of the universe, through dust clouds and intergalactic space, to reach our detectors. Together, the VLA telescopes, along with radio installations elsewhere, have opened new realms of the cosmos for us to study.

The VLA was built in the 1970s. With its recent upgrades, the observatory today carries a full observing load for astronomers in the U.S. and around the world. Its technicians and engineers move the dishes on railroad tracks around the site, creating the correct configuration of telescopes for the astronomers who have applied to use the installation. If astronomers want to focus on something extremely detailed, they can use the VLA in conjunction with telescopes stretching from St. Croix in the Virgin Islands to Mauna Kea on the Big Island of Hawai'i. This larger network is called the Very Large Baseline Interferometer (VLBI), and it creates a telescope with a resolving area the size of a continent. Using this larger array, radio astronomers have succeeded in measuring the event horizon around our galaxy's black hole, joined the search for dark matter in the universe, and explored the hearts of distant galaxies. 

The future of radio astronomy is big. There are huge new arrays built in South America, and under construction in Australia and South Africa. The VLA remains central to the work being done to understand the radio universe, and takes its rightful place with its newer siblings. Each of these arrays exists well apart from the radio noise generated by human civilization. Earth's deserts, each one with its own special ecological niches and landscapes, are also precious to radio astronomers. From those deserts, astronomers continue to explore the cosmos!