What can Radio waves tell us about the universe?
Radio waves can travel through interstellar dust and gas. This enables astronomers to see into dusty regions invisible to optical telescopes. Many molecules, including organic molecules, emit radio waves when they change energy level. For instance, Atomic Hydrogen, the most abundant material in space emits a radio wave with a wavelength of 21 cm when the spin of its electron flips over to reach a lower energy state. By tuning their instruments to the wavelength of atomic hydrogen, radio astronomers have inferred the earth’s location within the Milky Way as well as our galaxy’s motion and structure.
