The human side of science is revealed in this poignant tale of cosmological insight:

"At a press conference at the APS
April meeting in 1992 COBE speakers, including Smoot and Mather,
announced the discovery of variations at the level of parts per
hundred thousand against an overall average temperature of 2.7 K
(http://www.aip.org/pnu/1992/split/pnu077-1.htm ).

The microwave background is in effect the biggest thing we can see
(indeed it spreads out across the whole sky), the farthest-out thing
we can map, and the furthest-back in time. COBE was the first to
measure the variations and the first to provide a really precise
average temperature for the universe, 2.726 K

(http://www.aip.org/pnu/1993/split/pnu109-1.htm).

At the American Astronomical Society meeting where the this temperature was reported, an audible gasp was heard from the audience as the set of accumulated data points was placed on top of the expected blackbody spectrum---the fit between data and theory was that good. The COBE work represented a feat of great experimental science since the faint variations in the temperature of the distant CMB had to be measured against a foreground cloud of microwave radiation coming from our solar system, our galaxy, and other celestial objects.

Furthermore, the motion of Earth around the sun, the sun around the
Milky Way, and the Milky Way within our local cluster of galaxies
also had to be taken into account. "