what are the differences between an optical telescope, a radio telescope and an infrared telescope?

Question

Describe each of them and explain the types of situations or conditions ewach one is best suited to.

Answer 1

Optical telescopes.

These are the typical telescopes you use and see. They rely on a light source emitting in the Visible Spectrum of light (the rainbow :) ) They are good for looking at stars in the sky, the Moon, the sun (with a proper filter) and the planets.


Radio telescopes

These telescopes are not made of lenses, but instead are made in many ways. One way is to use copper wire to set up a radio antenna (kinda like one for your car). Another way is to use a Dish like a satellite dish.
Radio telescopes are good for looking at the planets and Sun in different ways. You gain different information about these objects by looking at data from their radio waves. They are difficult to use to see much further out into space, because the sun and Jupiter cause a lot of Radio noise. BUT! you can pick up background radiation from the BIG BANG with some radio telescopes. In other words, you can see into the past slightly and see after the Big Bang.

Infrared Telescope. It works like the optical scope, but it picks up infrared light instead of visible. It can be used to see many things, and sometimes provides stunning images of galaxies.

Answer 2

Infrared and optical telescopes are generally similar in design. Most research telescopes are Ritchey-Chretian designs, a type of compound telescope with a positive hyperboloid primary and negative hyperboloid secondary. Infrared mirrors may use different coatings than optical telescopes for better reflectivity in the infrared. For example, the Gemini telescopes, designed to function in both optical and infrared, have silver coatings rather than the usual aluminum. Infrared telescopes also need special thermal designs to avoid contaminating the image with thermal infrared. Because the atmosphere absorbs portions of the infrared spectrum, some infrared work is done by space telescopes. These are often cooled by liquid helium to eliminate thermal radiation.

Radio telescopes work at much longer wavelengths and are usually simple parabolic dishes. The surface tolerances for radio wavelengths are much more lenient than for optical or infrared, and the dishes can be made by ordinary metal fabrication techniques. Because resolution is proportional to the ratio between aperture and wavelength, radio telescopes must be much larger than optical telescopes to achieve similar resolution. This leads to apertures as large as 300 meters (the Arecibo dish) or the use of widely spaced arrays of dishes.

Of course, each type of telescope uses detectors appropriate to the wavelengths being used.

Answer 3

....Just a few additional thoughts which may help to clarify..
All of these different ways of seeing the universe are types of electromagnetic radiation, simply the same type of energy but at different frequencies.
Imagine you had a Radio Transmitter with a frequency dial that went all the way from zero Hertz ( cycles per second) to infinity.
Down around zero hertz to about 3000 hertz you would find some signals used for Beacons and other special communications. The signals from 20 Hertz to 20Kilohertz (20 Khz) are what we call sound waves which we can hear because the receptors in our ears are like a Radio receiver tuned to those frequencies.
from here, as you tune your radio to higher and higher frequencies, you go through the Low Frequency (LF) band, the Medium frequency (MF) band ( part of this, from550 to 1650 KHZ is our AM broadcast band) the HF Band goes up to about 30 Megahertz ( 30 million cycles /second) through VHF ( which contains our FM Broadcast and TV frequencies ) and so on until eventually reach the Infrared band. We can't hear or see these signals, but our body receptors feel them as heat. Above the infrared frequencies is the small band of frequencies to which the receptors in our eyes are tuned and which we call light.
Above the light frequency band you get into Ultraviolet, radar, then Xray and finally all the way up to gamma rays. As the frequencies go up, the radiation becomes more and more powerful until gamma rays so powerful they go right through the earth ( and your Body ) as a hot knife through butter.
We can build receivers for most of these signals, except the most powerfull ones. ( although we are trying.)
A star, or any other body that radiates energy, emits radiation in almost all of these energy forms. But each contains radiation due to different processes, elements and other conditions present in the object. By receiving and processing all the different forms of radiation, we can gather a fairly wide variety of information.
The different telescopes you mention are simply instruments designed to receive those particular frequencies and tranlate them to a form we we can interpret.
Thus, the Radio telescope is nothing more than a fancy version of a TV Disc Antenna but instead of hooking up a TV, we use special recorders etc. to show us the part of the info we are looking for. By the same token an Infrared telescope is basically a super fancy thermometer, measuring heat coming from an object.
I hope this helped a little.

Adolph

Answer 4

an optical telescope is one u look through a radio telescope picks up radio waves in the universe as far as it reaches and an infared telescope lets u see heat signals in the universe