The Largest Telescopes And Telescopes made to see Invisible E-M Radiation

Optical Mirrors & Large Scopes Optical mirrors are silvered on the front. So light doesn’t go through the glass. Thus… there is no chromatic aberration and imperfections in the glass do not matter as much If parabolic there is no spherical aberration and there is less sag Thus the largest astronomical telescopes are all… prime focus reflectors with parabolic mirrors

Multiple Mirror Scopes Recently to gather more light two or more telescopes are linked by computer. This creates an image that is brighter and has better resolution than either scope could produce on its own. The Gemini Telescopes, on the big island of Hawaii are a pair of linked telescopes

The Largest Telescopes For a long time the largest telescope was the one on Mt. Palomar here in So Cal. It has a 200” objective mirror For a while the largest was in Russia at 236” The Largest Telescope now is really four 8m scopes that work together, …the VLT Or “Very Large Telescope” It is in Chile, so it can see things in the sky of the Southern Hemisphere

Segemented Telescopes Gran Telescopio Canarias 10.5 m

Space Telescopes Scintillation or “twinkling” of a star is caused by unstable air refracting the star’s light in different directions. Light is also absorbed and scattered by the atmosphere This means that even an optical telescope works better in Space. Like Hubble Space Telescope: For “Deep Space” Kepler Space telescope: Looking for planet around other stars

Radio, X-ray and UV Telescopes Radio telescopes look and work like a satellite dish letting us “see” radio waves The “dish” is the objective. Infrared, UV and X-ray telescopes also let us “see” those wavelengths Because the atmosphere absorbs these wavelengths they are best placed in space

Detecting Light At first images in telescopes were seen by one person and had to be hand drawn by the astronomer to be shared. In the 1800s Film Cameras became available, though they weren’t used in telescopes until the 1900s. Objects then were photographed Now Charge-Coupled Devices (CCDs) are used to create images and are 20 times more sensitive to light as film. Now objects are digitally imaged

Computer aided imaging Most recently computers have been used to alter images. i.e. The light from a star can be subtracted so that we can see the planets orbiting it. False color images---that let you “see” invisible E-M waves like Infrared