Question

Astronomers cannot map all of the material in our galaxy using visible light.

a) Why is it that they cannot use visible light?

b) Which regions of the EM spectrum are used to map the galaxy?

Answer 1

Solution) (a) visible light is a narrow range of wavelengths of electromagnetic spectrum . As we cannot travel to a star or take samples of galaxy we depend on electromagnetic radiation to carry information to us from distant objects in space

Human eye is sensitive to small range of wavelengths called visible light and most objects in universe radiate at wavelengths we cannot see

So astronomers use telescopes with detection devices that are sensitive to wavelengths other than visible light allowing astronomers to study objects that emit this radiation otherwise invisible to human eye

(b) other than visible light other spectrum can be used to map galaxy

Visible light cannot be used as it is of shorter wavelengths

Spectrum of larger wavelengths can be used to map galaxy