The Astronomical Almanac is an interactive utility that can calculate the position of any astronomical object for any time, date and location on Earth. It also provides details for the Sun, Moon and planets.
A searchable database of features found on planets and satellites that the International Astronomical Union (IAU) has named and approved. This site includes images and information on nomenclature history and guidelines. Maintained by USGS Astrogeology Research Program in cooperation with other science and space agencies.
The Particle Data Group is an international collaboration charged with summarizing Particle Physics, as well as related areas of Cosmology and Astrophysics. The site contains a compilation and evaluation of measurements of the properties of the elementary particles.
A comprehensive physical reference data site from the National Institute of Standards and Technology (NIST). Contains databases, handbooks and links to molecular, atomic, spectroscopic data and much more. Also includes a calculator and searchable database of basic constants and conversion factors.
PhysLink.com is a comprehensive physics and astronomy online education, research and reference web site. It includes a glossary and information on astro-physical data, physical and math constants, conversion units, coefficients of friction and much more.
From the University of New South Wales in Sydney, Australia, this site contains tutorials that incorporate video demonstrations, animation and other multimedia tools to explain concepts such as constant acceleration, projectiles, energy and power, waves, electricity, magnetism and much more.