Caption: The all-sky image of the cosmic microwave background (CMB) from 9 years of WMAP data.

Features:

1. The Planck spacecraft has produced better data, but no equivalent image seems readily available.

2. The image displays temperature fluctuations (shown in different colors) from cosmic time ∼ 377,700(2300) years (after the Big Bang) that correspond to the density fluctuations that initiated galaxy formation throughout the observable universe. The image shows a temperature standard deviation (i.e., σ) of 100 microkelvins around the cosmic present CMB mean temperature T = 2.72548(57) K (Fixsen 2009). Put another way, the relative temperature variations are only 1 in 25000 (Wikipedia: Cosmic microwave background radiation: Features).

   Red is hottest, dark blue is coldest (see, e.g., Jarosik et al. 2010, p. 24).

3. The Milky Way foreground microwave has been subtracted using multi-frequency data. The CMB dipole anisotropy has also been subtracted.

4. The name of the original image file suggests that this all-sky oval sky map is in Mollweide projection (see NASA: WMAP: Nine Year Microwave Sky). In Mollweide projection, the equator is twice the length of the central meridian and shape and angle of features is sacrificed to some degree in favor of fairly accurate proportions in area.

5. A curious feature of this CMB sky map is that Stephen Hawking's (1942--) initials are embedded in it just a bit above the equator about 30 % of the semi-major axis left of center in dark blue. David Spergel (1961--) noticed this factoid at a conference and thought at first that it was a joke---but no Stephen Hawking really has initialed the universe.