Since radio waves can have very long wavelengths, standard radio telescopes need to be very large in order to obtain any sort of precision. But since building stadium size radio telescopes can be cost prohibitive (especially if you want them to have any steering capability at all), another technique is needed to achieve the desired results.

Developed in the mid-1940s, radio interferometry aims to achieve the kind of angular resolution that would come from incredibly large dishes without the expense. Astronomers achieve this by using multiple detectors in parallel with each other. Each one studies the same object at the same time as the others.

Working together, these telescopes effectively act like one giant telescope the size of the whole group of detectors together. For example, the Very Large Baseline Array has detectors 8,000 miles apart. Ideally, an array of many radio telescopes at different separation distances would work together to optimize the effective size of the collection area as well improve the resolution of the instrument.

With the creation of advanced communication and timing technologies, it has become possible to use telescopes that exist at great distances from each other (from various points around the globe and even in orbit around the Earth). Known as Very Long Baseline Interferometry (VLBI), this technique significantly improves the capabilities of individual radio telescopes and allows researchers to probe some of the most dynamic objects in the universe.

Radio's Relationship to Microwave Radiation

The radio wave band also overlaps with the microwave band (1 millimeter to 1 meter). In fact, what is commonly called radio astronomy, is really microwave astronomy, although some radio instruments do detect wavelengths much beyond 1 meter.

This is a source of confusion as some publications will list the microwave band and radio bands separately, while others will simply use the term "radio" to include both the classical radio band and the microwave band.

Vocabulary:

radio emissions – радиоизлучение cycle of frequency – цикл частоты radio frequencies – радиоволны emit – выделять, излучать

active galaxies (AGN) – активная галактика

rotating neutron stars – вращающиеся нейтронные звезды

Fermi Gamma-ray Space Telescope – космический гамма-телескоп Ферми detectable wavelengths – обнаруживаемые длины волн

radio interferometry – радиоинтерферометрия

Spot Beam

A spot beam is a beam of radio signals that is directed towards a specific area on the Earth’s surface. Spot beams are the opposite of broad beams, which are beams that are directed towards a large area of the Earth’s surface. While broad beams are used

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