The cosmic fireball

The round speckled green object (superimposed on a picture of sunrise in our garden) is extracted from a representation of the most important scientific observation since Darwin: a picture of the universe at an age of about 400,000 years — that's about 2 hundred-thousandths of the age of the universe. To put this earliness another way: it's the same fraction of its life so far as a photograph of me when I was a baby 15 hours old.

The picture was taken from a satellite called WMAP. From the 1970s up to this observation (or rather, its less accurate predecessors) cosmologists had inferred the “big bang” from indirect evidence, but now we can observe the hot expanding gas cloud that these words indicate in amazing detail.

(This particular artistic modification of the picture is borrowed from Mark Tegmark's web site)