For centuries, telescopes had grown bigger and better, the view clearer and sharper. However, once telescopes had reached a size that allowed them to see quite well, astronomers encountered a problem unrelated to the telescope’s design.
It was the Earth’s atmosphere. As light passes through the atmosphere, it can be bent in unpredictable ways by warm and cool air pockets. This meant astronomers were constantly studying the skies through a shimmering field — as though they were trying to see objects through a heat haze.
When we look at the stars with our naked eyes, the atmosphere makes it look as though the stars are twinkling. When astronomers use telescopes to take a picture of a celestial object through the atmosphere, the details are blurry.
The blurriness prevented astronomers from realizing the full potential of the powerful telescopes they built. It limited the view from the ground no matter how large the telescope.
When astronomers want to study the skies by viewing other types of radiation, the atmosphere is even more of a problem. Earth’s atmosphere allows visible light and radiowaves to pass through but blocks out most other radiation, including X-rays and gamma rays. Radiation, such as that from infrared or ultraviolet rays, is partially blocked.