Butterfly of Galaxies
When astronomers look out into the universe, they notice that the objects they see are not distributed willy-nilly. Rather, the force of gravity tends to bring galaxies together into giant agglomerations such as clusters, superclusters, sheets, and walls.
Researchers have scanned the skies and produced incredible maps showing the distribution of the nearest galaxies. While these maps tend to stay within about 7 billion light years from Earth, some surveys have discovered distant quasars — enormous sources of light from the early universe –- as much as four times that distance.
In the largest survey, the Sloan Digital Sky Survey, astronomers have so far mapped more than one-third of the sky and plotted the location of 500 million individual objects. The image above comes from the 6dF Galaxy Survey, currently the third largest sky survey.
The picture has its peculiar shape because astronomers have to aim their telescopes away from the bright light of the Milky Way galaxy, which obscures the sections of the sky in the center of the image.