After nearly a decade of design and construction, the Sloan Digital Sky Survey saw first light on its giant mosaic camera in 1998 and entered routine operations in 2000. While the collaboration and scope of the SDSS have changed over the years, many of its key principles have stayed fixed: the use of highly efficient instruments and software to enable astronomical surveys of unprecedented scientific reach, a commitment to creating high quality public data sets, and investigations that draw on the full range of expertise in a large international collaboration. The generous support of the Alfred P. Sloan Foundation has been crucial in all phases of the SDSS, alongside support from the Participating Institutions and national funding agencies in the U.S. and other countries.

The Sloan Digital Sky Survey has created the most detailed three-dimensional maps of the Universe ever made, with deep multi-color images of one third of the sky, and spectra for more than three million astronomical objects.

In its first five years of operations, the SDSS carried out deep multi-color imaging over 8000 square degrees and measured spectra of more than 700,000 celestial objects. With an ever-growing collaboration, SDSS-II (2005-2008) completed the original survey goals of imaging half the northern sky and mapping the 3-dimensional clustering of one million galaxies and 100,000 quasars. SDSS-II carried out two additional surveys: the Supernova Survey, which discovered and monitored hundreds of supernovae to measure the expansion history of the universe, and the Sloan Extension for Galactic Understanding and Exploration (SEGUE), which extended SDSS imaging towards the plane of the Galaxy and mapped the motions and composition of more than a quarter million Milky Way stars.

SDSS-III (2008-2014) undertook a major upgrade of the venerable SDSS spectrographs and added two powerful new instruments to execute an interweaved set of four surveys, mapping the clustering of galaxies and intergalactic gas in the distant universe (BOSS), the dynamics and chemical evolution of the Milky Way (SEGUE-2 and APOGEE), and the population of extra-solar giant planets (MARVELS).

The latest generation of the SDSS (SDSS-IV, 2014-2020) is extending precision cosmological measurements to a critical early phase of cosmic history (eBOSS), expanding its revolutionary infrared spectroscopic survey of the Galaxy in the northern and southern hemispheres (APOGEE-2), and for the first time using the Sloan spectrographs to make spatially resolved maps of individual galaxies (MaNGA).

This is the “Science blog” of the SDSS. Here you’ll find short descriptions of interesting scientific research and discoveries from the SDSS. We’ll also update on activities of the collaboration in public engagement and other arenas. We’d love to see your comments and questions about what you read here!

You can explore more on the SDSS Website.