![]() ![]() 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. ![]() Instead, astrophysicists use special detectors to observe gamma rays and to figure out where they come from in the sky.The differing wavelengths among the various energies create different instrumental needs. They go straight through optics used for other wavelengths, making them impossible to reflect or refract. Gamma rays are the universe’s most energetic form of light. Engineers at NASA’s Goddard and Marshall Space Flight Centers have designed mirrors like these for missions like the X-ray Imaging and Spectroscopy Mission (XRISM) and the Imaging X-ray Polarimetry Explorer (IXPE). Since there’s a lot of empty space in the middle of a single paraboloid, X-ray mirrors incorporate multiple mirrors as nested onion-like shells. This is called a grazing incidence mirror. To detect them, engineers turn the mirrors on their sides so the X-rays can skip off the surface. X-rays can simply pass through the atoms that make up most telescope mirrors. X-ray mirrors use the slightly angled side of the paraboloid. The Webb mirror, for example, is coated with a thin layer of gold so that it can reflect infrared light. Telescope mirrors are coated with different materials depending on the color of the light they need to reflect. (Backyard telescopes can also have mirrors, too.)Īn X-ray Mirror Assembly built for the X-ray Imaging and Spectroscopy Mission consists of a primary and secondary mirror, each containing 812 nested foil mirror segments. Large mirrors can be made thinner and lighter than lenses of the same size, which makes reflecting scopes ideal for sending to space. Reflecting telescopesĪ telescope that uses a mirror as its primary optical element is called a reflecting telescope. The first telescopes, developed in the 1600s, were refractors, as are many backyard telescopes today.īut very large lenses make refracting telescopes large and heavy, which makes them difficult to use in space. Like eyeglasses, the lenses bend, or refract, light passing through them. Refracting telescopesĪ telescope using a lens for its main optical element is called a refracting telescope. The larger a mirror or lens, the more light it collects, and the better its ability to detect fainter objects. The size of the main mirror or lens determines how well a telescope can collect light. Astronomers observe distant cosmic objects using telescopes that employ mirrors and lenses to gather and focus light. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |