Editing Cosmic noise (section)

== History ==
[[Karl Guthe Jansky|Karl Jansky]], an American physicist and radio engineer, first discovered [[radio wave]]s from the [[Milky Way]] in August, 1931. At [[Bell Labs|Bell Telephone Laboratories]] in 1932, Jansky built an antenna designed to receive radio waves at a frequency of 20.5&nbsp;[[Hertz|MHz]], which is a wavelength of approximately 14.6&nbsp;meters.

After recording signals with this antenna for several months, Jansky categorized them into three types: nearby thunderstorms, distant thunderstorms, and a faint steady hiss of an unknown origin. He discovered the location of maximum intensity rose and fell once a day, which led him to believe he was detecting radiation from the [[Sun]].

A few months went by following this signal thought to be from the Sun, and Jansky found that the brightest point moved away from the Sun and concluded the cycle repeated every 23 hours and 56 minutes. After this discovery, Jansky concluded the radiation was coming from the [[Milky Way]] and was strongest in the direction of the center of the [[galaxy]].

Jansky's work helped to distinguish between the radio sky and the [[Optics|optical]] sky. The optical sky is what is seen by the human eye, whereas the radio sky consists of daytime meteors, solar bursts, quasars, and gravitational waves.

Later in 1963, American physicist and radio astronomer [[Arno Allan Penzias]] (born April 26, 1933) discovered  [[Cosmic microwave background|cosmic microwave background radiation]]. Penzias's discovery of  cosmic microwave background radiation helped establish the [[Big Bang]] theory of cosmology. Penzias and his partner, [[Robert Woodrow Wilson]] worked together on ultra-sensitive cryogenic [[microwave]] receivers, originally intended for radio astronomy observations. In 1964, upon creating their most sensitive antenna/receiver system, the [[Holmdel Horn Antenna]], the two discovered a radio noise they could not explain. After further investigation, Penzias contacted [[Robert H. Dicke|Robert Dicke]], who suggested it could be the background radiation predicted by cosmological theories, a radio remnant of the [[Big Bang]]. Penzias and Wilson won the [[Nobel Prize in Physics]] in 1978.

=== NASA's work ===
The [[ARCADE|Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission]] (ARCADE) is a device designed to observe the transition out of the "cosmic dark ages" as the first stars ignite in nuclear fusion and the [[universe]] begins to resemble its current form.<ref>{{Cite web |title=ARCADE – Absolute Radiometer for Cosmology, Astrophysics, Diffuse Emission |url=https://asd.gsfc.nasa.gov/archive/arcade/ |access-date=2021-04-09 |website=asd.gsfc.nasa.gov}}</ref>

ARCADE consists of 7 precision [[radiometer]]s carried to an altitude of over 35&nbsp;km (21&nbsp;miles) by a [[Research balloon|scientific research balloon]]. The device measures the tiny heating of the early [[universe]] by the first generation of stars and galaxies to form after the [[Big Bang]].