Most people think of a "telescope" as something in a backyard or the dome at the local planetarium. But telescopes like these that detect the kind of light we can see with our human eyes are just one answer. Stopping there would be like saying, we have cars to get around, who needs airplanes?
Light takes on many forms - from radio to infrared to X-rays and more. And the Universe tells its story through all of these different types of radiation. So, in order to really understand the cosmos, astronomers need all different kinds of telescopes.