Astronomy Hubble Telescope Secrets of the Universe

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Hubble Telescope

Secrets of the Universe

Not since Galileo turned his telescope towards the heavens in 1610 has any event so changed our understanding of the universe as the deployment of the Hubble Space Telescope (HST). Galileo's telescope used a simple arrangement of two lenses in a long, narrow tube. Galileo was able to see objects 10 times more clearly than ever before possible.

A telescope is an amazing device that has the ability to make faraway objects appear much closer.. Telescopes you see today come in one of two designs: Refractor telescope, which uses glass lenses and the Reflector telescope, which uses mirrors instead of the lenses.

Hans Lippershey of Middleburg, Holland, gets credit for inventing the refractor in 1608, and the military used the instrument first. Galileo was the first to use it in astronomy. Both Lippershey's and Galileo's designs used a combination of convex and concave lenses.

About 1611, Kepler improved the design to have two convex lenses, which made the image upside-down. Kepler's design is still the major design of refractors today, with a few later improvements in the lenses and the glass to make them.

Refractors have good resolution, high enough to see details in planets and binary stars. However, it is difficult to make large objective lenses (greater than 4 inches or 10 centimeters) for refractors. Refractors are relatively expensive, if you consider the cost per unit of aperture. Because the aperture is limited, a refractor is less useful for observing faint, deep-sky objects, like galaxies and nebulae, than other types of telescopes.

Isaac Newton developed the reflector about 1680, in response to the chromatic aberration (rainbow halo) problem that plagued refractors. Instead of using a lens to gather light, Newton used a curved, metal mirror (primary mirror) to collect the light and...