REPORT OF DISCUSSION CLUB

SESSION NO.6(B)

Topic:The Space Telescopes

Presenter: Shanawaz Shaikh

Date:18 February,2020.

The Space Telescopes

Now that we have seen the origin of Telescopes, it is time to look at the evolution of these machines that allow us to look back in time...a time machine if you will.



William Herschel

Fun Fact: Sir William Herschel(A British Astronomer) was the first to realise that telescopes are time machines, through which we could look back in time.

light takes 8 minutes to reach us from the Sun , thus the Sun is 8 light minutes away from the Earth, similarly the Moon is 1 light second away from the Earth. So everything we see in the night sky is merely an illusion, in reality thkngs are way far ahead than where they seem to be.... interesting, isn't it?





Why put telescopes in space, what's the point?

There's many reasons for that,

•It is really difficult to observer anything from earth on a cloudy night, thus it really helps to put the Telescope above the clouds, thus capturing as much light as we can.

•Light Pollution is another important reason. There's a lot of light sources in cities which makes it really due to reflection and scattering,spread all around and thus makes it harder to observe the stars, which would be more clearly observed in darkness.

A comparison of the night sky in rural and urban areas.

•Even if these are avoided, there are some frequencies of light that do not reach us, for example the Ozone layer(20 to 30 km above the Earth's surface) prevents any Ultraviolet light from entering the Earth, and thus makes it difficult to detect.

•Also , there are different kind of temperature fluctuations in the atmosphere, which makes the light refract in air thus passing through different regions and making the image blur.





Cultural reasons :

Besides the scientific reason , there are some cultural reasons. For example, most of the big telescopes on Earth are located on Hilltops or dormant mountains to avoid any kind of clouds or atmospheric disturbances. The proposed Thirty Metre Telescope, the largest Telescope on Earth was going to be built on Mauna Kea, a dormant volcano in Hawaii. But the indigenous Hawaiian's consider the land sacred and there has been an ongoing quarell back and forth between the Astronomers and the residents. But, we do her their point though, nobody would like ii if someday soneone comes to our house and starts taking our land for their work, it's their home after all.





THE HUBBLE SPACE TELESCOPE.





The HST is one of the first big space telescopes Launched by NASA. It specialises in Visible and UV light.

The size of HST is about the size of a school bus!

Here are some interesting facts about the Hubble telescope

Edwin Hubble, the Astronomer who discovered that the Universe is expanding based on the contributions by Henrietta Leavitt, one of the greates unsung heroes of science. It was named after, the Astronomer who discovered that the Universe is expanding based on the contributions by, one of the greates unsung heroes of science.

NASA has different Telescopes in space that specialises in different band of electromagentism.

Chandra X-Ray telescope

The Chandra X-Ray telescope , named after Indianastrophysicist,Subrahamanyan Chandrashekhar, the first astrophysicist to win the Nobel Prize.

Compton Gamma Ray Telescope

It was named after Arthur Compton , also known in Quantum mechanics for Compton effect. This Telescope is fine tuned for Gamma rays!

Spitzer Telescope

Named after Lyman Spitzer, a physicist who first proposed the idea of putting a telescope in space . This specialises in Infrared light.





The future of Space Telescopes:





The James Webb Space Telescope

This is an expanding frontier , where new developments are being made consistently, and we eagerly await for the launch of The James Webb Space Telescope, which is supposed to be launched in 2021.

The Telescope is soo big, it wouldn't fit in the fairings of the probe that's going to launch it, so it curls up like the petals of a flower, gets launched then diploys and then unfurls...a truly Innovative mechanism.

It is named after James Webb , the head of NASA whole we were going to the Moon!

Fun fact: This is the only Telescope not named after a physicist!!!

The size of the mirror of James Webb Space Telescope compared to that of Hubble.

How would you repair Telescopes in Space?

The answer to that question is really simple, you send Astronauts in space to repair the Telescopes.

Astronauts repairing the HST

This is a very skillful task that requires a lot of patience and technicality.

Fun Fact: In the beginning of the movie Gravity, Sandra Bullock and her team sports to be repairing something in Space, before things go wrong. They were repairing the Hubble Space Telescope.





"Somewhere, something incredible is waiting to be known"-Carl Sagan