Speeding Through the Universe
Credit: DMR, COBE, NASA, Four-Year Sky Map; APOD - 1/14/04
Our Earth is not at rest. The Earth moves around the Sun. The Sun orbits the
center of the Milky Way Galaxy. The Milky Way Galaxy orbits in the Local
Group of Galaxies.The Local Group falls toward the Virgo Cluster of Galaxies.
But these speeds are less than the speed that all of these objects together move
relative to the cosmic microwave background (CMB). In the above all-sky map,
radiation in the Earth's direction of motion appears blueshifted and hence
hotter, while radiation on the opposite side of the sky is redshifted and colder.
The map indicates that the Local Group moves at about 600 km/sec
relative to this primordial radiation. This high speed was initially
unexpected and its magnitude is still unexplained.
Why are we moving so fast? What is out there?