Scientists follow established laws of physics in building telescopes, and an all-wave telescope would have to break those laws. With present technology, it is not possible to build one telescope able to efficiently survey the entire electromagnetic spectrum. "And low-frequency radio telescopes don't bear the remotest resemblance to X-ray telescopes." "Low-frequency radio telescopes look wildly different from microwave telescopes, even though both study the radio portion of the spectrum," he states. Phillips says that telescopes designed for different parts of the electromagnetic spectrum often look dramatically unlike one another. Right: A mosaic of different astronomical phenomena at various wavelengths. These differences in the interaction between matter and energy have resulted in telescopes designed to only accommodate very specific wavelengths. Radio waves will reflect from a metal that X-rays pass right through. Because this date was the 7th anniversary of Kenya's independence, the satellite was named Uhuru (Swahili for "freedom").ĭifferent energy wavelengths interact with matter in different ways. NASA's first X-ray telescope was launched from Kenya on Dec. Although high altitude balloons and rockets can provide X-ray and gamma ray data, the best results come from satellites orbiting completely outside the Earth's atmosphere. Studies of astronomical objects in high energy X-rays and gamma rays began in the early 1960s. The atmosphere does such a good job that telescopes designed to detect these portions of the electromagnetic spectrum have to be positioned outside the atmosphere. The Earth's atmosphere scatters or absorbs high-energy radiation, protecting us from the damaging effects of UV, X-rays and gamma rays. By the 1940s, scientists were launching rockets with rudimentary UV detectors onboard. The Earth's stratospheric ozone layer, located 20 to 40 kilometers above the Earth's surface, blocks out UV wavelengths shorter than 300 nanometers. Ultraviolet telescopes have to be placed even higher than infrared telescopes. Left: The NASA Infrared Telescope Facility 3.0 meter telescope at the summit of Mauna Kea, Hawaii. Infrared telescopes are placed on mountaintops, far above the low-lying water vapor that interferes with infrared light. Their telescopes must therefore always be positioned high above the ground or in space. Infrared and ultraviolet light are affected more dramatically by the 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. Radio and optical telescopes can be used on Earth, but some resolution is lost due to Earth's atmosphere. An example of a modern radio telescope is The Very Large Array in New Mexico (right), composed of 27 antennas electronically combined to give the resolution of an antenna 36 kilometers (22 miles) across. We generate a large amount of noise on Earth as well, so smaller telescopes would lose some astronomical radio signals amid our daily production of rock music, television broadcasts and cellular phone calls. Radio telescopes also need to be large in order to overcome the radio noise, or "snow," that naturally occurs in radio receivers. Low-frequency radio waves would be unfocused and fuzzy in smaller telescopes. When most people think of telescopes they think of visible light, or optical, telescopes. Most of the universe is invisible to us because we only see the visible light portion of the electromagnetic spectrum. But as the technology advances and becomes more specialized, differences among telescope designs become more pronounced As our knowledge of physics improves, scientists are able to develop increasingly superior telescopes. Although the first telescope was created 400 years ago, we didn't have a complete picture of the electromagnetic spectrum until the early part of this century. This energy is in the form of electromagnetic waves. The atomic matter that forms the telescope has to somehow interpret the energy emitted from astronomical objects. Telescopes rely on the interaction between energy and matter. Radio has long wavelengths and low energies, while gamma rays have very short wavelengths and high energies. This results in dissimilar, incompatible detecting devices. The differing wavelengths among the various energies create different instrumental needs.
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