It is a very interesting question. How can scientists discover that any exopalnets or moons have water bodies on their surface without going there or without any landing of satellites or robots which give us pictures to see them.
So in this article I have to tell you how this process takes place but before starting we need to understand about the characteristics of light.
Electromagnetic Spectrum
As we all learn about the electromagnetic spectrum in our junior classes in school. In the electromagnetic spectrum we learn that light has different colours of wavelengths and on the basis of these wavelengths light is divided into 7 parts.
1. Radio wave 2. Microwave 3. Infrared 4. Visible 5. Ultra violet
6. X-ray 7. Gamma rays
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| Credit :- Radio2space |
We all are able to see these colourful worlds with our eyes. Only the visible part of light and we cannot see any other part of light with our naked eyes. There are many colours of different wavelengths in the visible part like red, green, blue, yellow, orange etc.
How can scientists discover water on other planets ?
Now we know about light and its different wavelengths but how it helps scientists to know about the presence of water on exoplanets and moons. We understand these with an example. So let’s imagine the colour of a plant. Yes it is green because of chlorophyll present in them which is green in colour. If we pass a light through a green leaf and measure the upcoming wavelengths of light then it is absurd that all colour wavelengths are absorbed by the leaf but only green colour wavelength is reflected back.
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| Credit :- ScienceDirect,com |
Similarly, if we pass light in water then it absorbs all colour wavelengths but only reflected blue colour wavelength.
So this process or we say this idea is used by scientists to know about the presence of water on other planets. Scientists make machines which capture the light coming from other planets and draw the graph of wavelengths and see the amount of wavelengths and which colour wavelength is blocked more. And with the help of this data scientist concluded about the presence of water.
Technology used in telescope
This technology is almost used in all telescopes but the most famous telescope which used this technology more perfectly is “James webb telescope”. The JWST is equipped with advanced technology such as an infrared telescope, and it has been designed mainly to detect infrared light.
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| Credit :- Wikipedia |
Infrared waves are emitted by those thighs who radiate heat .That’s why the telescope will capture stars, galaxies and planets because they all emit some amount of heat. And it is able to see through the cosmic dust, gas clouds, and other obstructions that block visible light.
I hope that it is sufficient to answer the question. But if you would like to know more about James Webb telescope and more interesting facts than many blogs available on our website, please check it out there.