reflectors
Radio telescopes, refracting telescopes, and reflecting telescopes all use mirrors or lenses to collect and focus incoming electromagnetic radiation. The main difference is the wavelength of the radiation they are designed to study – radio telescopes focus on radio waves, refracting telescopes focus on visible light, and reflecting telescopes focus on a variety of wavelengths including visible light, ultraviolet, and infrared.
They use telescopes, but different types of telescopes. There are telescopes for radio waves, microwaves, infrared light, visible light, ultraviolet light, x-rays, and gamma rays, all depending on what it is you're trying to see.
Most telescopes collect and focus light from distant objects in space, such as stars, planets, and galaxies. This focused light is then magnified and analyzed by astronomers to study and make observations about the universe.
Because the visible light coming from the stars is so faint that during the day the light form our local star (the Sun) is so bright that it swamps the starlight. Thus to make observations using visible light, astronomers have to do so at night.
Those terms are most commonly used for optical telescopes. However, the same design can be used for non-visible frequencies; for example, radio telescopes of the "satellite dish" variety are essentially reflecting telescopes.
Radio telescopes, refracting telescopes, and reflecting telescopes all use mirrors or lenses to collect and focus incoming electromagnetic radiation. The main difference is the wavelength of the radiation they are designed to study – radio telescopes focus on radio waves, refracting telescopes focus on visible light, and reflecting telescopes focus on a variety of wavelengths including visible light, ultraviolet, and infrared.
Galileo's telescope is what is called a refractory visible light telescope. It takes visible light and uses lenses to condense a lot of light down to what will fit into your eye. It was very rudimentary and could not see very much detail. Today, there are still refractory visible light telescopes. In fact, these are used by amateur astronomers to capture excellent pictures of the universe around us. They are limited in their aperture however (the size of the opening pointed toward the stars). There are many other kinds of telescopes now also. Reflecting telescopes can be much bigger. Currently, the largest are the Keck telescopes in Hawaii where there are two that have an aperture of 10 meters, where as Galileo's was only 10-25 mm. Besides visible light, we now use telescopes to see all the wavelengths of light, from radio waves through microwaves, infrared, ultraviolet, X-ray and gamma rays.
They use telescopes, but different types of telescopes. There are telescopes for radio waves, microwaves, infrared light, visible light, ultraviolet light, x-rays, and gamma rays, all depending on what it is you're trying to see.
Most telescopes collect and focus light from distant objects in space, such as stars, planets, and galaxies. This focused light is then magnified and analyzed by astronomers to study and make observations about the universe.
Because the visible light coming from the stars is so faint that during the day the light form our local star (the Sun) is so bright that it swamps the starlight. Thus to make observations using visible light, astronomers have to do so at night.
There are several astronomical telescopes in orbit. The most famous is of course the Hubble, but COROT, MOST, and the Swift Gamma-Ray Burst Observer are all visible light telescopes in orbit around Earth, and there's another - Kepler - that doesn't orbit Earth, but does orbit the Sun. There are also a multitude of orbital telescopes that use segments of the electromagnetic spectrum other than visible. Spitzer, for example, uses infrared light (it's another solar orbiter).
Most to all of the milky way is visible through sattelite telescopes as well as other galaxies, but only our local spiral arm is visible from here.
Those terms are most commonly used for optical telescopes. However, the same design can be used for non-visible frequencies; for example, radio telescopes of the "satellite dish" variety are essentially reflecting telescopes.
One advantage of reflecting telescopes is that the mirrors can be very big. Large mirrors allow reflecting telescopes to gather more light than refracting telescopes do. Another advantage is that curved mirrors are polished on their curved side, which prevents light from entering the glass. Thus any flaws in the glass do not affect the light. A third advantage is that mirrors can focus all colors of light to the same focal point. Therefore, reflecting telescopes allow all colors of light from an object to be seen in focus at the same time.
All of it. White light is the blend of all visible colors.
Nowadays, the bulk of the work astronomers do is on computers. They spend a small portion of their time at telescopes actually taking data. Astronomically-useful telescopes rarely have eyepieces you can look through. Radio, ultraviolet, or infrared telescopes collect light that you can't even see with your eye! Telescopes that collect visible light often have electronic cameras called CCD cameras that create an image in a computer. Many telescopes are used to create a spectrum (the light is split into a rainbow, and the brightness of each color is measured). Radio telescopes record signals that astronomers can reconstruct using a computer to make an image or a spectrum.
If the lights from all visible wavelengths are combined, they appear to be a white color.