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Why is it difficult to study the Milky Way Galaxy with optical telescopes?
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Galaxy
The Whirlpool Galaxy (left), also known as M51, an Sc galaxy accompanied by a small irregular companion galaxy, NGC 5195 (right).
Studying the Milky Way Galaxy with optical telescopes is difficult primarily because of the presence of interstellar dust within the interstellar medium.1
These minute dust grains, which occupy the regions between stars, scatter and absorb starlight. Because this dust is opaque to optical wavelengths, it blocks the light emitted by many celestial objects, preventing them from being seen clearly from Earth. While long-wavelength radiation, such as radio and far-infrared waves, can penetrate this dust freely, optical light is significantly obscured. Consequently, astronomers must often rely on infrared astronomy to observe regions of the galaxy that are otherwise hidden by these dense clouds of gas and dust.123