How do astronomers learn about the invisible Universe with detectors and telescopes

In this new Hubblecast episode, Dr. J guides us through the fifth chapter of Eyes on the Skies, the International Astronomical Union s movie celebrating the telescope on its 400th anniversary in 2009. The Universe is a black void, with a scattering of stars, nebulae and galaxies or so it appears to observers using visible light. But if we include other forms of radiation invisible to us, the picture changes completely: clouds of interstellar hydrogen gas, emitting radio waves; stellar nurseries, glowing