Telescopes are devices used to observe the universe. There are many different types and some are even sited in space.

Optical telescopes observe visible light from space. Small ones allow amateurs to view the night sky relatively cheaply but there are very large optical telescopes sited around the world for professional astronomers to use.

Disadvantage:

Radio signals also travel at the speed of light. This means that they take a long time to travel through the Solar System. For example, it takes just over one second for a signal to reach the Moon from the Earth, and up to 21 minutes to reach Mars.

Stars are very far away from each other. The distances are measured in light years. One light year is the distance that light travels in one year. Since the speed of light in space is about 300,000,000 m/s, this is a very large distance indeed - about 9.5 million million km.

One of the earliest tools for space exploration was the telescope. Using lenses and mirrors to see beyond Earth's borders, telescopes gave scientists their first glimpses of what exists beyond Earth's atmosphere.

For example, the telescope is no longer an Earth-bound instrument. In 1990, the Hubble Space Telescope was launched into outer space. In the last 20 years, it has brought us images of our universe that couldn't have been captured in any other way.

It's a miraculous piece of technology that's powered by sunlight. With many different cameras and types of scientific instruments, the Hubble Space Telescope has provided scientists with invaluable data. In fact, NASA estimates that data from the Hubble Space Telescopehas been used as the basis of over 10,000 scientific papers in the past two decades!

X-rays are partly blocked by the Earth's atmosphere and so X-ray telescopes need to be at high altitude or flown in balloons.

an atmosphere and equipment to remove waste gases such as carbon dioxide.
insulation and heating to provide a suitable temperature for life.
exercise equipment to reduce the effects of weightlessness, such as weakened bones.

 

Telescopes are devices used to observe the universe.

Optical telescopes  observe visible light from space. Small ones allow amateurs to view the night sky relatively cheaply but there are very large optical telescopes sited around the world for professional astronomers to use.

Optical telescopes on the ground have some disadvantages:

Radio telescopes detect radio waves coming from space. Although they are usually very large and expensive, these telescopes have an advantage over optical telescopes. They can be used in bad weather because the radio waves are not blocked by clouds as they pass through the atmosphere. Radio telescopes can also be used in the daytime as well as at night.

A space observatory is any instrument in outer space which is used for observation of distant planets, galaxies, and other outer space objects.

A large number of observatories have been launched into orbit, and most of them have greatly enhanced our knowledge of the cosmos.

Performing astronomy from the Earth's surface is limited by the filtering and distortion of electromagnetic radiation due to the Earth's atmosphere.

This makes it desirable to place astrononomical observation devices into space.

As a telescope orbits the Earth outside the atmosphere it is subject neither to twinkling (distortion due to thermal turbulences of the air) nor to light pollution from artificial light sources on the Earth.

But space-based astronomy is even more important for frequency ranges which are outside of the optic window and the radio window, the only two wavelength ranges of the electromagnetic spectrum that are not severely attenuated by the atmosphere.

For example, X-ray astronomy is nearly impossible when done from the Earth, and has reached its current important stand within astronomy only due to orbiting satellites with X-ray telescopes such as the Chandra observatory or XMM-Newton observatory.

"I have learned to use the word 'impossible' with the greatest caution," said Wernher von Braun who was leading what came to be known as the Rocket Team.

The history of exploration took the next logical step –- venturing into outer space. The new explorers of the 20thcentury embraced the sentiment of Russian space pioneer Konstantin Tsiolkovsky.

"The Earth is the cradle of humanity," he said, "but one cannot live in a cradle forever."

On Oct. 3, 1957, scientists and engineers in the Soviet Union were the first to take a small step out of the "cradle" when they launched the world's first satellite, Sputnik 1.

Optical telescopes- Over the centuries, telescopes evolved from simple hand-held objects to mounted beasts on mountain-top observatories and finally to telescopes orbiting the earth in outer space, which introduced the advantage of eliminating atmospheric distortion of the visual field. Today's telescopes are capable of seeing almost to the edge of the known universe.
Radio telescopes- Radio telescopes detect celestial objects not using the light waves they emit but using the radio waves. These telescopes are built in the form of parabolic dishes. Visible objects such as stars and galaxies emit radio waves as well as light waves, others can only be detected by radio telescopes.