Caltech astronomer George Djorgovski stands in front of a portion of The Big Picture, a monumental mural that covers an entire wall at Los Angeles’s historic and newly renovated Griffith Observatory. He led the team that created the image, which depicts a portion of the cosmos in the Virgo constellation, using actual data from the Palomar-Quest digital sky survey. “We wanted to inspire the public and convey the richness of the deep universe and to do it with a real scientific data set,” says Djorgovski.

The Big Picture Show

Wider than the original Cinerama Dome movie screen in Hollywood, the largest astronomical image ever produced has been put on public view in Los Angeles, thanks to Caltech scientists who hope to inspire the public with the wonders of space exploration. The image depicts well over a million astronomical objects in a slice of sky in the Virgo constellation. It has been reproduced as a giant mural in the new exhibit hall of the landmark Griffith Observatory, which reopened November 3 after several years of renovation.

A team led by Caltech Professor of Astronomy George Djorgovski created the image using data from the Palomar-Quest digital sky survey, an ongoing project at the Samuel Oschin Telescope at Palomar Observatory, which is owned and operated by Caltech. The survey is a joint venture between groups at Caltech and Yale.

In a city renowned for its ongoing love affair with the cinematic blockbuster, the great cosmic panorama, named The Big Picture, is 152 feet long by 20 feet high. That’s nearly twice the width of the old curved screen in the famous Cinerama Dome, although it’s not quite as tall. The mural, which is displayed on 114 steel-backed porcelain enamel plates, covers the entire wall of the Richard and Lois Gunther Depths of Space exhibit hall at the observatory, where millions of visitors are expected to view it annually.

“We wanted to inspire the public and convey the richness of the deep universe and its understanding, and to do it with a real scientific data set,” says Djorgovski. “We are doing research with these data, but there is also a sense of beauty and awe, which is important to communicate, especially to young people.”

The image represents only a sliver of the visible sky, less than a thousandth of the celestial sphere, roughly the area covered by an average index finger held about a foot away from the eyes. The entire Palomar-Quest sky survey from which this slice is taken covers an area about 500 times larger.

“What is perhaps most striking about the image is the wealth of the information in it, and the remarkable diversity of cosmic objects it shows,” says Ashish Mahabal, the project scientist for the survey. The part of the sky covered by The Big Picture spans the core of the Virgo cluster of galaxies, about 60 million light years distant from Earth. Along with the prominent bright galaxies in the cluster, the panels contain nearly a million fainter and more distant galaxies, as well as hundreds of thousands of stars in the Milky Way, a thousand quasars (the most distant and luminous objects in the universe), hundreds of asteroids in our own solar system, and at least one comet.

The data used to construct the image were obtained in 2004 and 2005 by the Caltech–Yale team in the course of more than 20 nights at Palomar’s Oschin Telescope. Several hundred gigabytes of raw data were then distilled to produce a 7.4-gigabyte color image, using cutting-edge technology at Caltech’s Center for Advanced Computing Research.

“This project illustrates a powerful synergy between modern astronomy and advanced computing, which is increasingly becoming a driving force for both research and education,” says Roy Williams, PhD ’83, a scientist on the team and one of the leaders of the U.S. National Virtual Observatory, a collaboration of organizations whose aim is to unify access to astronomical data. “We plan to use The Big Picture as a magnet and a gateway to learning, not only about the universe, but also about the computing and information technology used to create the mural.”

Sky surveys are a large part of the scientific history and legacy of Palomar Observatory, starting with the pioneering work of Caltech professor Fritz Zwicky in the 1930s. A major photographic sky survey conducted in the 1950s at the 48-inch telescope provided the first modern atlas of the sky, guiding many astronomical inquiries. The telescope was later named in honor of Samuel Oschin, the late Los Angeles business leader and philanthropist.

Several other exhibits at Griffith Observatory also have strong connections to Caltech and Palomar. These include a model of the 200-inch Hale Telescope, which was a major engineering feat at the time of its construction in 1948 and has since been at the center of many groundbreaking astronomical discoveries.

The Caltech team that created The Big Picture includes Djorgovski; staff scientists Mahabal, Williams, Matthew Graham, and Andrew Drake; graduate students Milan Bogosavljevic and Ciro Donalek; digital image experts Leslie Maxfield ’95, Simona Cianciulli, and Radica Bogosavljevic; and several staff members at Palomar Observatory and the Center for Advanced Computing Research. The work was supported mainly by the National Science Foundation.

For more online information on The Big Picture, please go here.