Infrared telescope how does it work

Many features only work on your mobile device. If you like what you see, we hope you will consider buying. Get the App. But as the technology advances and becomes more specialized, differences among telescope designs become more pronounced.

Most of the universe is invisible to us because we only see the visible light portion of the electromagnetic spectrum. When most people think of telescopes they think of visible light, or optical, telescopes. When the first optical telescope appeared in the s, the design was simple - one concave and one convex lens fitted inside a tube. The tube acted as a receiver, or 'light bucket'. The lenses bent, or refracted, the light as it passed through the glass and thus made the scene appear 3 to 4 times larger.

Galileo improved upon the design and by had developed a power refracting telescope. Galileo made the telescope famous when he discovered the valleys and mountains of the moon and spotted four of Jupiter's satellites. The glass lenses in the Galileo telescope weren't very clear, however - they were full of little bubbles and had a greenish tinge due to the iron content of the glass.

Also, the shape of the glass lenses gave the field of view very fuzzy edges. The magnification of Galileo's telescope could only be improved by focusing the light farther behind the primary lens, which resulted in longer and longer telescopes.

But once. Right : Johannes Hevelius' ft. Reprinted with permission by the Royal Astronomical Society, London.

Isaac Newton invented the first reflecting telescope in By using a curved mirror to reflect and focus the light inside the tube, he was able to reduce the length of the telescope dramatically. The reflecting telescope solved another problem inherent in the refracting telescope: chromatic aberration.

In , Newton. By , Newton's reflecting telescope had caught on with the scientific community. Even today, large optical telescopes are. But it wasn't until the s that astronomers even began looking for other parts of the electromagnetic spectrum. Karl Jansky inadvertently discovered galactic emissions of radio waves in Working at Bell Telephone Laboratories, Jansky was trying to find what caused short-wave radio interference in Trans-Atlantic communications.

By building a rotating radio telescope to look at the. Left : The "Jansky Antenna" doesn't look much like modern aerials, i. Like optical telescopes, radio telescopes have reflectors and receivers.

Most radio telescopes need to be large in order to accommodate radio's longer wavelengths and lower energies. Resolution is also a factor:. Radio and optical telescopes can be used on Earth, but some resolution is lost due to Earth's atmosphere. By viewing from the other side of the sky, the Hubble Space Telescope allows astronomers to see the universe without the distortion and filtering that occurs as light passes through the Earth's atmosphere.

Infrared and ultraviolet light are affected more dramatically by the Earth's atmosphere. Their telescopes must therefore always be positioned high above the ground or in space. Ultraviolet telescopes have to be placed even higher than infrared telescopes. The Earth's stratospheric ozone layer, located 20 to 40 kilometers above the Earth's surface, blocks out UV wavelengths shorter than nanometers.

Infrared telescopes use fundamentally the same components and follow the same principles as visible light telescopes; namely, some combination of lenses and mirrors gathers and focuses radiation onto a detector or detectors, the data from which are translated by computer into useful information.

The detectors are usually a collection of specialized solid-state digital devices: the most commonly used material for these is the superconductor alloy HgCdTe mercury cadmium telluride. To avoid contamination from surrounding heat sources, the detectors must be cooled by a cryogen such as liquid nitrogen or helium to temperatures approaching absolute zero; the Spitzer Space Telescope, which at its launch in was the largest ever space-based infrared telescope, is cooled to C and follows an innovative Earth-trailing heliocentric orbit whereby it avoids the reflected and indigenous heat of the Earth.

Water vapor in the Earth's atmosphere absorbs most infrared radiation from space, so ground-based infrared telescopes must be sited at high altitude and in a dry environment to be effective; the Observatories at Mauna Kea, Hawaii, are at an altitude of m. Atmospheric effects are reduced by mounting telescopes on high-flying aircraft, a technique used successfully on the Kuiper Airborne Observatory KAO , which operated from to The effects of atmospheric water vapor are, of course, eliminated altogether in space-based telescopes; as with optical telescopes, space is the ideal location from which to make infrared astronomical observations.

The first orbital infrared telescope, the Infrared Astronomy Satellite IRAS , launched in , increased the known astronomical catalog by about 70 percent. Infrared telescopes can detects objects too cooland therefore too faintto be observed in visible light, such as planets, some nebulae and brown dwarf stars.