[2] At the time of its design, the SDSS was a pioneering combination of novel instrumentation as well as data reduction and storage techniques that drove major advances in astronomical observations, discoveries, and theory.

In the approximate decade it took to achieve these goals, SDSS contributed to notable advances in massive database storage and accessing technology, such as SQL, and was one of the first major astronomical projects to make data available in this form.

The model of giving the scientific community and public broad and internet-accessible access to the survey data products was also relatively new at the time.

The collaboration model around the project was also complex but successful, given the large numbers of institutions and individuals needed to bring expertise to the system.

In July 2020, after a 20-year-long survey, astrophysicists of the Sloan Digital Sky Survey published the largest, most detailed 3D map of the universe so far, filled a gap of 11 billion years in its expansion history, and provided data which supports the theory of a flat geometry of the universe and confirms that different regions seem to be expanding at different speeds.

These images are processed to produce lists of objects observed and various parameters, such as whether they seem pointlike or extended (as a galaxy might) and how the brightness on the CCDs relates to various kinds of astronomical magnitude.

[10] The image of the stars in the focal plane drifts along the CCD chip, and the charge is electronically shifted along the detectors at the same rate, instead of staying fixed as in tracked telescopes.

The Sloan Legacy Survey covers over 7,500 square degrees of the Northern Galactic Cap with data from nearly 2 million objects and spectra from over 800,000 galaxies and 100,000 quasars.

The information on the position and distance of the objects has allowed the large-scale structure of the Universe, with its voids and filaments, to be investigated for the first time.

[16] The Sloan Extension for Galactic Understanding and Exploration obtained spectra of 240,000 stars (with a typical radial velocity of 10 km/s) to create a detailed three-dimensional map of the Milky Way.

It comprised four separate surveys:[22] The APO Galactic Evolution Experiment (APOGEE) used high-resolution, high signal-to-noise infrared spectroscopy to penetrate the dust that obscures the inner Galaxy.

[23] APOGEE surveyed 100,000 red giant stars across the full range of the galactic bulge, bar, disk, and halo.

[24] The high-resolution spectra revealed the abundances of about 15 elements, giving information on the composition of the gas clouds the red giants formed from.

Sound waves that propagate in the early universe, like spreading ripples in a pond, imprint a characteristic scale on the positions of galaxies relative to each other.

It was expected to detect between 150 and 200 new exoplanets, and was able to study rare systems, such as planets with extreme eccentricity, and objects in the "brown dwarf desert".

[28][31] The original Sloan Extension for Galactic Understanding and Exploration (SEGUE-1) obtained spectra of nearly 240,000 stars of a range of spectral types.

Building on this success, SEGUE-2 spectroscopically observed around 120,000 stars, focusing on the in situ stellar halo of the Milky Way, from distances of 10 to 60 kpc.

[32] Combining SEGUE-1 and 2 revealed the complex kinematic and chemical substructure of the galactic halo and disks, providing essential clues to the assembly and enrichment history of the galaxy.

The fourth generation of the SDSS (SDSS-IV, 2014–2020) is extending precision cosmological measurements to a critical early phase of cosmic history (eBOSS), expanding its 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).

By using two-dimensional arrays of optical fibers bundled together into a hexagonal shape, MaNGA was able to use spatially resolved spectroscopy to construct maps of the areas within galaxies, allowing deeper analysis of their structure, such as radial velocities and star formation regions.

The raw data (from before being processed into databases of objects) are also available through another Internet server and first experienced as a 'fly-through' via the NASA World Wind program.

There are also KML plugins for SDSS photometry and spectroscopy layers,[39] allowing direct access to SkyServer data from within Google Sky.