The "Big Picture" is a single continuous digital sky image, a cut through the core of the Virgo Cluster of galaxies, derived from the Palomar-Quest digital sky survey. It is reproduced on porcelain tiles as a 152 ft long by 20 ft high back wall of the new exhibit hall (Gunther Depths of Space) at the Griffith Observatory. This website is its home in cyberspace. The image is a window into the distant universe, and it conveys a remarkable richness of the sky, as seen through a modern telescope.

This image contains nearly a million faint galaxies, about half a million stars in our own Galaxy (the Milky Way), about a thousand distant quasars, about a thousand asteroids in our own Solar System, and at least one comet. You can learn more about these objects here.

The image covers a swath of the sky which is 2 degrees wide, and 15.2 degrees long (i.e., about 4 times as wide as the disk of the full Moon, and about 30 times as long), which is less than a thousandth of the entire celestial sphere. It is about an area covered by your extended index finger, held about a foot away from your eyes.

A key idea behind this exhibit is to use a real scientific data set, rather than an artist's impression, to illustrate the range of scales and the richness of phenomena observed in the Universe. The data used to create the image were obtained at the Samuel Oschin Telescope at Palomar Observatory, in the course of 20 nights in 2004 and 2005, as a part of the Palomar-Quest (PQ) digital sky survey, a collaborative project between Yale University and Caltech. In this survey, large areas of the sky are scanned repeatedly, and the data are combined later. The survey covers a total area about 300 times larger than what is shown in the"Big Picture", and the data are still being analyzed by the Yale and Caltech scientists.

These survey data were processed at the Center for Advanced Computing Research (CACR) at Caltech, using a cutting-edge computing technology, as a part of a broader effort to create a Virtual Observatory. The PQ survey has collected about 20 Terabytes of data so far, a few hundred Gigabytes of which were used in the construction of the "Big Picture". The actual color image displayed on the wall is about 7.5 Gigabytes in size. You can learn more about the process used to create this image here.