![]() ![]() In 1990, the Hubble Space Telescope was carried into orbit by the Space Shuttle. It was completed in 1957 and had a 250-foot diameter radio dish that could be aimed into the sky. Over the next 400 years, there have been astronomical advances, but all of the telescopes have two things in common: they have light gathering abilities and they magnify.ĭuring WWII, Sir Bernard Lovell had worked on radar and after the war in the 1950s he made plans for a large radio telescope. In 1789 in England, William Herschel built the first giant reflector telescope, which was 12 meters long. His new improved telescope eliminated chromatic aberration, was cheaper to build, simpler in design, had a wider field of view, and was portable. ![]() This coloring is called chromatic aberration and it causes fringe coloring, so that images look blurred. Newton’s idea was to use mirrors so that the creation of colors by the lens could be eliminated. Up to that point, telescopes were refracting and used a lens which worked much like the prisms Newton was using. In 1668, Sir Isaac Newton built the first reflecting telescope in order to prove his theory that white light had a spectrum of colors. He drew the moon’s phases, was able to describe the Milky Way, and discovered the rings of Saturn and the moons of Jupiter.īecause he became convinced that Earth and the planets circled the Sun, he was arrested by the Catholic Inquisition and imprisoned until he died in 1642. In 1609, Galileo heard about Lippershey’s invention and began building his own design making many improvements so that the magnification of his telescope reached 20 times.Īccording to history, Galileo looked to the skies and was able to see the craters of the moon. His ‘looker’ was made by fitting one concave piece of glass to a convex piece of glass. He called his invention the ‘looker’ and was able to magnify things to three times their normal size. We just use other mirrors to flip it back.The first person to patent a telescope was Hans Lippershey, a Dutch eyeglass maker, in 1608. Have you ever looked into a spoon and noticed your reflection is upside down? The curved mirror in a telescope is like a spoon: It flips the image. ![]() Also, since mirrors are one-sided, they are easier than lenses to clean and polish.īut mirrors have their own problems. It is much easier to make a large, near-perfect mirror than to make a large, near-perfect lens. So the mirror just has to have the right curved shape. Light is concentrated by bouncing off of the mirror. A bigger mirror does not also have to be thicker. Unlike a lens, a mirror can be very thin. ![]() It would be like looking through a dirty window.Ī telescope that uses mirrors is called a reflecting telescope. Any flaws in the lens will change the image. Also, as they get thicker the glass stops more of the light passing through them.īecause the light is passing through the lens, the surface of the lens has to be extremely smooth. Heavy lenses are hard to make and difficult to hold in the right place. If you want to see far away, you need a big powerful lens. People with especially poor eyesight need thick lenses in their glasses. In a telescope, it makes faraway things seem closer.Ī simple refracting telescope uses lenses to make images bigger and more visible. In eyeglasses, this makes things less blurry. It’s hard to make a perfect mirror, but it’s even harder to make a perfect lens.Ī telescope made with lenses is called a refracting telescope.Ī lens, just like in eyeglasses, bends light passing through it. If they do have such problems, the image gets warped or blurry and is difficult to see. They can’t have any spots, scratches or other flaws. That means the mirrors and lenses have to be just the right shape to concentrate the light. The optics of a telescope must be almost perfect. That light is what we see when we look into the telescope. Light is then concentrated by the shape of the optics. The bigger the mirrors or lenses, the more light the telescope can gather. To do that, the optics-be they mirrors or lenses-have to be really big. The mirrors or lenses in a telescope are called the “optics.” Really powerful telescopes can see very dim things and things that are really far away. So why do we use mirrors today? Because mirrors are lighter, and they are easier than lenses to make perfectly smooth. The first telescopes focused light by using pieces of curved, clear glass, called lenses. Most telescopes, and all large telescopes, work by using curved mirrors to gather and focus light from the night sky. A telescope is a tool that astronomers use to see faraway objects. ![]()
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