The earth is surrounded by layers of gases called the atmosphere. Some wavelengths of electromagnetic waves arriving from space are absorbed by the atmosphere and never reach the surface of our planet.

Take a look at the following diagram. The earth's atmosphere absorbs the majority of ultraviolet, X-, and gamma rays, which are all shorter wavelengths than visible light.

High energy X- and gamma rays would damage organisms and cells of creatures if they were to reach the earth's surface directly. Fortunately, the atmosphere protects life on earth. Long-wavelength radio waves and infrared rays also do not reach the surface.

The electromagnetic waves we can generally observe on the ground consist of visible light, which is difficult for the atmosphere to absorb, near-infrared rays, and some electromagnetic waves. These wavelength ranges are called atmospheric windows. Ground-based astronomical observation employs optical and radio telescopes that take advantage of atmospheric windows. Infrared, X-, and gamma rays, for which atmospheric windows are closed, can only be observed using balloons and astronomical satellites outside the earth's atmosphere.