Most distant quasar—redshift 5 (the faint red dot at the arrow.)

An unassuming speck of red light assumed gargantuan proportions in 2000, when scientists at the Sloan Digital Sky Survey used detection and computational techniques borrowed from particle physics to find the most distant object ever observed. This quasar had the highest redshift ever seen, corresponding to a distance of 27 billion light years from Earth. Redshift (meaning the light appears shifted to the red end of the spectrum) is used as a measure of the distance of celestial objects. Because the universe is expanding, the quasar was only about 4 billion light years from Earth when the light seen now was emitted-at a time when the universe was very young, less than 1 billion years old. Quasars are compact, luminous objects believed to be the high-energy nuclei of young galaxies. Finding distant quasars is a specialty of the Sky Survey, launched in 2000 as the most ambitious astronomical survey ever. It will exceed all predecessors in scale, mapping in detail one-quarter of the entire sky and producing more sensitive and accurate images than ever made before by using electronic light detectors instead of photographic techniques. The project involves 11 universities and other institutions, including Fermi National Accelerator Laboratory. The telescopes are located in New Mexico.

Scientific Impact: The Sky Survey is producing a field guide to the universe that will be used by scientists for decades to come. It will have a significant impact on astronomical studies ranging from the origin and evolution of galaxies to the properties and distribution of the dust from which stars like the sun were created.

Social Impact: The Sky Survey is extending the practice of mapmaking—laying the gridwork for reality—to cosmography, the science of mapping the universe and determining the place of humans in it. It will enhance 100-fold humans' three-dimensional picture of the universe, producing a quantity of information rivaling the content of the Library of Congress.

Reference: "The Discovery of a Luminous z=5.80 Quasar from the Sloan Digital Sky Survey," X. Fan et al., to be published in Astron. Journal.

URL: http://www.sdss.org/science/

Technical Contact: Prof. Michael Turner, mturner@oddjob.uchicago.edu

Press Contact: Jeff Sherwood, DOE Office of Public Affairs, 202-586-5806

SC-Funding Office: Office of High Energy and Nuclear Physics