Caption: The all-sky sky map (probably in Mollweide projection) of the cosmic microwave background (CMB) from 9 years of WMAP data.

For many other versions, see Google images: planck cmb all sky

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 primordial density fluctuations at the recombination era t = 377,770(3200) Jyr = 1.192*10**13 s (z = 1089.80(21)) which initiated structure formation (AKA large-scale structure formation) throughout the observable universe. The CMB temperature standard deviation (i.e., σ) is ∼ 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 (in dark blue) are embedded in it ∼ 1/3 of the way left of center along the semi-major axis and just a bit above the semi-major axis. 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. The initials are a bit less obvious in other sky map of the CMB.