| When we look up on a dark night, we see a sky filled with stars. The light from a star, like the light from a flashlight or a lightning bug, is one form of electromagnetic radiation. Light is formed of waves, and different colors of light have different wavelengths. Red light has a longer wavelength than blue light. But the colors we see with our eyes represent only a tiny piece of the story. The electromagnetic spectrum spans from radio waves, with wavelengths longer than a car, to gamma-rays, with wavelengths smaller than the nucleus of an atom. We can learn a great deal by looking at things with our eyes, or with optical telescopes. But different parts of the spectrum may reveal a very, very different picture. credit: NASA/CXC/SAO source: chandra.harvard.edu |
