Optical telescopes are used in observatories around the world. The optical telescopes in
observatories are reflecting telescopes. Reflecting telescopes use mirrors to gather and
focus light from distant objects.
Optical telescopes are built in high, dark places. The height reduces distortion caused by
heat and Earth's atmosphere. Less distortion means that starlight entering the telescope is
clearer. The telescope needs to be built in a dark place to reduce the interference from electric lights. Stars are much dimmer in the city because of the city lights.
How do optical telescopes work?
Light from a distant object enters the reflecting telescope through its open end. Light moves down to a large curved minor called the primory minor. This collects the light and brings it to a point.
This light bounces off the primary mirror and heads towards a smaller mirror called
the secondary mirror. This mirror reflects the image to an eyepiece on the side of the
The information sent to the eyepiece is stored on a computer. Astronomers use the computer to produce images of the object and study these images rather than looking
through the eyepiece.
Amazing Facts about Space :
Before people ventured into spoce, scientists sent animals, so they could observe how the animals coped with being in spoce. The dog, Laika, was the first mammal from Earth to orbit the planet. Laika died from stress and overheating during her 1957 space mission in the Russian spacecraft Sputnik 2.
As telescopes have become more powerful, they have allowed us to observe planets, galaxies and nebulae in greater detail. In 1990 the Hubble telescope was sent into orbit
Galileo discovered four moons orbiting Jupiter in January 1610.
The Indian Astronomical Observatory which sits 4517 metres above sea level, in Hanle,
India, is the world's highest observatory telescope.
Amateur astronomers use refracting telescopes The earliest telescopes were all refracting
telescopes including the famous and very simple telescope used by Galileo Galilei in the early 1600s.
The Keck telescopes, the world's largest optical telescopes, are located on the dormant Mauna Kea volcano on the island of Hawaii.
Hubble is the size of a large school bus. It fits inside the cargo bay of a space shuttle.
The Hubble Space Telescope spotted young brown dwarfs for the first time in the Orion Nebula. Brown dwarfs are so-called failed stars because they are too small to be ordinary stars — they cannot sustain nuclear fusion in their cores the way our Sun does.
Hubble is serviced and newer technology is installed by astronouts on space walks. This
means that Hubble can benefit from the same advances as ground-based telescopes.
The Hubble Space Telescope completes one full orbit of Earth every 97 minutes.
A three-stage rocket, Saturn V, was used to take astronauts to the Moon in the Apollo
spacecraft. Stage 1 burnt its fuel over 2 minutes and 30 seconds - then separated from the rest of the rocket ond fell back to Earth. Stage 2 then fired and lifted the astronauts into space. It too fell away. Finally, Stage 3 fired for 2 minutes and 30 seconds and sent Apollo into orbit around Earth. Stage 3 fired again for over five minutes to send Apollo
towards the Moon. It then fell away from the spacecraft. All spacecraft and satellites are taken into space by rockets.
The largest and most powerful rocket ever built was the Saturn V rocket.
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