Astronomy Picture of the Day

Explanation: Is this our universe? Possibly. It is one computerized guess of how gas in the universe was distributed billions of years ago, at redshift 3, when the universe was only a quarter of its present age. Using supercomputers at the National Centre for Supercomputing Applications and assumptions about the composition and beginning of the universe, the GC3 team was able to reconstruct a hypothetical universe. A cube of this universe was cut out and displayed, with each side being about 8 million light years across. Colour represents temperature of the hot gas. At the bottom a single slice through this cube is displayed, with helium abundance superposed with a wire mesh. The small structures appearing here give insight into the past and present structure of the intergalactic medium, the matter inhabiting the regions between galaxies and clusters of galaxies.