Editing Cosmic microwave background (section)

===COBE===
After a lull in the 1970s caused in part by the many experimental difficulties in measuring CMB at high precision,<ref name=PartridgeReview/>{{rp|8.5.1}}
increasingly stringent limits on the anisotropy of the cosmic microwave background were set by ground-based experiments during the 1980s. [[RELIKT-1]], a Soviet cosmic microwave background anisotropy experiment on board the Prognoz 9 satellite (launched 1 July 1983), gave the first upper limits on the large-scale anisotropy.<ref name=PartridgeReview/>{{rp|8.5.3.2}}

The other key event in the 1980s was the proposal by [[Alan Guth]] for [[cosmic inflation]]. This theory of rapid spatial expansion gave an explanation for large-scale isotropy by allowing causal connection just before the epoch of last scattering.<ref name=PartridgeReview/>{{rp|8.5.4}} With this and similar theories, detailed prediction encouraged larger and more ambitious experiments.

The [[NASA]] Cosmic Background Explorer ([[Cosmic Background Explorer|COBE]]) satellite orbited Earth in 1989–1996 detected and quantified the large-scale anisotropies at the limit of its detection capabilities.
The [[NASA]] [[Cosmic Background Explorer|COBE]] mission clearly confirmed the primary anisotropy with the Differential Microwave Radiometer instrument, publishing their findings in 1992.<ref>
{{cite journal|last=Smoot|first=G. F.|date=1992|title=Structure in the COBE differential microwave radiometer first-year maps|journal=[[Astrophysical Journal Letters]]|volume=396|issue=1|pages=L1–L5|doi=10.1086/186504|bibcode=1992ApJ...396L...1S| s2cid=120701913 |display-authors=etal|doi-access=free}}</ref><ref>
{{cite journal|last=Bennett|first=C.L.|year=1996|title=Four-Year COBE DMR Cosmic Microwave Background Observations: Maps and Basic Results|journal=[[Astrophysical Journal Letters]]|volume=464|pages=L1–L4|doi=10.1086/310075|bibcode=1996ApJ...464L...1B|arxiv = astro-ph/9601067 |s2cid=18144842|display-authors=etal}}</ref> The team received the [[Nobel Prize]] in physics for 2006 for this discovery.