When we think “telescope”, we picture peering through a viewfinder or viewing images of the stars. However, visible light is only a small part of the electromagnetic spectrum; we can learn much about our galaxy by viewing visible light’s less frequent older brother, the radio wave. Radio telescopes are the technological descendants of actual radios (like the one in your car!). Karl Jansky, who worked for Bell Telephone Laboratories, created a large radio antenna to test for sources of static which would interfere with radio telephone calls. He identified static from nearby thunderstorms, but heard a constant “faint hiss.” This “faint hiss” was radiation from the universe, concentrated in the Milky Way galaxy.
Radio telescopes typically look like huge dishes with an antenna. Currently, astronomers often use radio interferometers: series of connected radio telescopes. While radio interferometers are used to observe information about galaxies, planets, and nebulae, some of the most groundbreaking work in radio astronomy is taking place examining cosmic background radiation. Cosmic background radiation is the thermal radiation left behind from the Big Bang. Differences in radio frequencies of cosmic background radiation reveals early differences in temperature which dictated how stars and galaxies form. Thus, radio telescopes can reveal how and why the universe formed the way it did.
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The CMB and our ability to observe it is pretty crazy. I am fascinated by the fact that we could even think to look for it and then interpret the radio waves into useable information.
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This was a really cool post; when we first learned about radio waves, I didn’t even think that they would be connected to the Cosmic Background Radiation. Discovering the source of Jansky’s “faint hiss” was such an essential step toward understanding the history of the universe. Do you think that there are other aspects of the Big Bang or major cosmic events that we have not yet observed because we do not have the technological capability to detect other types of waves with needed resolution? Maybe there is something like the CMB that would be critical in understanding the composition of the universe that could only be detected with a high-resolution gamma wave telescope!
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Grader here!
Great post about radio telescopes and the CMB, not many people realize how much more there is to astronomy outside the visual wavelengths. Even cooler, the CMB was detected by accident. The signal was detected and no one even knew what it was–it was actually thought to be bird droppings at first! When we realized that it wasn’t from anywhere near us, even in our galaxy, that’s when we knew we had landed on something cool!
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