COBE Dipole: Speeding Through the Universe
Credit: NASA, COBE, DMR, Four-Year Sky Map
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.
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
microwave background.
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 kilometers per second 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?