© The 2dF Galaxy Redshift Team, 30 June 2003. Reproduced by permission of Commonwealth of Australia.
The Two-degree-Field Galaxy Redshift Survey released this data set in 2003. The survey measured the Doppler shift (redshift) of 100,000 galaxies in thin slices of the sky (indicated in units of hour angle around the edge of the image) out to a distance of 2 billion light-years. The survey results show how galaxies are distributed in huge clusters and long filaments, leaving large empty voids in some regions of space. The size of these structures is telling—if the universe were entirely made of normal matter, even larger structures would be expected to emerge. (Unit: 10)