Optical telescopes use either lens' (refractory) or mirrors (reflective) to magnify light. Radio telescopes use dishes to pick up radio waves. sensors on the dishes collect the waves and turn them into a picture
Radio telescopes are much larger than optical telescopes because of wavelength. Earth's atmosphere has two major "windows" where it is transparent to photons: 300 nm - 800 nm: optical wavelength window (approximate) 30 mm - 30 m: radio wavelength window (approximate) Even the shortest-wavelengths used by radio telescopes at around 30 mm are still thousands of times longer than the longest wavelengths used by optical telescopes. The wavelength has 2 effects on the size of a telescope: * The angular resolution (in order to distinguish 2 nearby stars, FWHM) depends on the wavelength/aperture ratio. Radio-frequency photons require a wider aperture to focus than visible-light-frequency photons, so radio telescopes *must* be larger to get a reasonable resolution. * A telescope typically requires the collecting area to be aligned within 1/10 of the wavelength it is designed for. Because it is almost impossible to get all the parts of a sufficiently large telescope aligned to within 80 nm, radio telescopes *can* be built much larger.
Quasars and some pulsars are dim in the visible light range. In the radio spectrum, however, they're extremely bright, and as such observing them in telescopes that observe these wavelengths is more beneficial.
I can think of two big reasons right off the top of the bat:1). Radio signals are influenced by a trip through the atmosphere much less thanoptical ones are, so the downside of observing them from the surface is far less.2). Radio telescopes operate at wavelengths that are perhaps 15,000 times thewavelengths at which optical instruments do. So for comparable sensitivity andresolution, a radio telescope has to be 15,000 times the size of an optical one.Armed with this fact, your average Congressperson is not likely to support theprogram to fund a proposed Jansky Space Radio Telescope.
Quasars are the brightest and most distant objects in the known universe. In the early 1960's, quasars were referred to as radio stars because they were discovered to be a strong source of radio waves. In fact, the term quasar comes from the words, "quasi-stellar radio source". Today, many astronomers refer to these objects as quasi-stellar objects, or QSOs. As the resolution of our radio and optical telescopes became better, it was noticed that these were not true stars but some type of as yet unknown star-like objects. It also appeared that the radio emissions were coming from a pair of lobes surrounding these faint star-like objects. It was also discovered that these objects were located well outside our own galaxy. Quasars are very mysterious objects. Astronomers today are still not sure exactly what these objects are. What we do know about them is that they emit enormous amounts of energy. They can burn with the energy of a trillion suns. Some quasars are believed to be producing 10 to 100 times more energy than our entire galaxy. All of this energy seems to be produced in an area not much bigger than our solar system.
Yes, that's correct. The longer wavelengths of radio waves mean that radio telescopes have poorer angular resolution compared to optical telescopes. This is because resolving power is inversely proportional to the wavelength of the electromagnetic waves being observed.
Radio telescopes are generally much larger than optical telescopes for two reasons: First, the amount of radio radiation reaching Earth from space is tiny compared with optical wavelengths, so a large collecting area is essential. Second, the long wavelengths of radio waves mean that diffraction severely limits the resolution unless large instruments are used.
The reflector of your telescope's mirror DOES need to be finely polished, with no disturbances bigger than a half-wavelength or so. So for optical telescopes, the mirror must be smooth to nanometers. But for a radio telescope which measures wavelengths in meters or centimeters, a fine wire mesh will generally do the trick. And since radio telescopes tend to be very large, the finer the mesh the lighter the dish can be - and therefore, more easily rotated and pointed.
Optical telescopes use either lens' (refractory) or mirrors (reflective) to magnify light. Radio telescopes use dishes to pick up radio waves. sensors on the dishes collect the waves and turn them into a picture
The three major types are the optical, the infrared, and the radio telescopes. There are other specialized instruments for observing gamma rays, or x-rays, or for doing processes such as interferometry. Among the optical telescopes are the refracting (lens), reflecting (mirror) and compound telescopes (computer-assisted combinations of several smaller telescopes to simulate a much larger one).
Radio telescopes are much larger than optical telescopes because of wavelength. Earth's atmosphere has two major "windows" where it is transparent to photons: 300 nm - 800 nm: optical wavelength window (approximate) 30 mm - 30 m: radio wavelength window (approximate) Even the shortest-wavelengths used by radio telescopes at around 30 mm are still thousands of times longer than the longest wavelengths used by optical telescopes. The wavelength has 2 effects on the size of a telescope: * The angular resolution (in order to distinguish 2 nearby stars, FWHM) depends on the wavelength/aperture ratio. Radio-frequency photons require a wider aperture to focus than visible-light-frequency photons, so radio telescopes *must* be larger to get a reasonable resolution. * A telescope typically requires the collecting area to be aligned within 1/10 of the wavelength it is designed for. Because it is almost impossible to get all the parts of a sufficiently large telescope aligned to within 80 nm, radio telescopes *can* be built much larger.
No, a radio telescope is designed to detect radio waves, which have much longer wavelengths than visible light. Visible light cannot be studied using a radio telescope as it operates in a different part of the electromagnetic spectrum. To study visible light, astronomers typically use optical telescopes.
Radio telescopes allow us to see things that can't be seen in visible light. And vice versa, optical telescopes can show things that are not visible in radio telescopes. So, the information from both kinds of telescopes really complements each other.
" RAY-dee-oh TELL-uh-skope"
Quasars and some pulsars are dim in the visible light range. In the radio spectrum, however, they're extremely bright, and as such observing them in telescopes that observe these wavelengths is more beneficial.
It is not necessary to do so, as atmosphere doesn't distort radio signals as much as visible light.
Modern tools and equipment used to study the universe include optical telescopes, radio telescopes, space telescopes, the electromagnetic spectrum, many branches of science including Paleontology, physics, chemistry, Biology, etc., computer science and much much more. For more about tools and equipment used in astronomy, see the related links.