Albert Einstein 

NASA

The NASA Astrophysics Data System   --  approximately 300,000 free full-text articles
The NASA Astrophysics Data System (ADS) is a NASA-funded project that provides free access to the full text of articles in astronomy and astrophysics. Most of the major astronomical journals are included.
arXiv.org   --  is a fully automated electronic archive and distribution server for research papers. Covered areas include physics and related disciplines, mathematics, nonlinear sciences, computational linguistics, and neuroscience. Both preprints and published papers are available.

Physics and Astronomy

• Physics & Astronomy (Springer)
• Astrophysics Data System (ADS) -- NASA-funded project whose main resource is an Abstract Service, which includes four sets of abstracts: 1) astronomy and astrophysics, 2) instrumentation, 3) physics and geophysics, 4) Los Alamos preprint server. Each dataset can be searched by author, object name (astronomy only), title, or abstract text words. In addition, links to the full text of articles appearing in most of the major astronomical journals.

Astronomy

• Ask the Space Scientist
• Astronomy and Physics Java Applets
• Astronomy Pictures
• CNN.com: Space
• Constellations, The -- the brief introduction
• Curious about Astronomy, Ask an Astronomer -- Cornell Unoversity.
• Dicovery Channel - Space Guide
• ESA Space Science News -- European Space Agency
• Galileo Project, The
• Greek Astronomy
• Guardian: Space Exploration
• Guide to Astronomy, A  -- This handy page serves both as a dictionary and as the site index. Most words in the dictionary are also links, and if you click on them, it will take you to the page where they are described in full.
• History of Astronomy
• Hubble Space Telescope Public Pictures
• Hubble Space Telescope Home Page
• Mars Pathfinder
• MSNBC: Space News
• MyStarsLive
• National Virtual Observatory A collaboration of US astronomical organizations to unify access to astronomical data.
• Nine Planets (A Multimedia Tour of the Solar System)
• NSSDC Photo Gallery
• Online NewsHour: Space Exploration
• Particle Adventure, The
• Ptolemy's Geography
• SpaceDaily -- Asia Pacific Space Centre
• SpaceDaily -- Online space news
• Space.com
• StatCodes -- On-line statistical software for astronomy and related fields
• Sunspots
• SUPARCO - Pakistan Space and Upper Atmosphere Research Commission
• Time - Space
• Virtual Sky A portal to the night sky, with imagery from multiple sources, including a high-resolution optical sky survey(DPOSS) and engravings from the seventeenth century.
• Yahoo! - Space News

Physics

• Accel-OneD Solver -- browser-interactive resource for solving low and high speed constant acceleration problems at U. Of Missouri Columbia
• Center for History of Physics -- American Institute of Physics
• Century of Physics -- The American Physical Society
• Fowler's Physics Applets -- Basic concepts of Physics.
• Fundamental Physical Constants
• Interactive Physics & Math with Java
• Math and Physics Help Page, The
• NIST Physical Reference Data  -- Includes physical constants, atomic spectroscopic data, molecular spectroscopic data, ionization data, x-ray & gamma-ray data, radiation dosimetry data, nuclear physics data and condensed matter physics data.
• NTNU Virtual Physics Laboratory by Fu-Kwun Hwang   -- Java Applets about mechanics, dynamics, waves, thermodynamics, electromagnetics and light/optics.
• Physics 2000 - an interactive journey through modern physics
• Physics (Color Science)
• Physlets -- Physics Applets, are small flexible Java applets designed for science education.
• PhysLink
• Resources of the Niel's Bohr Library -- Materials relating to the history of modern physics and allied sciences. Includes books, journals, archives, manuscripts, a catalogue of sources, photographs and oral history interviews.
• Why is the Sky Dark at night (Applet guide to Physics problems)

Libraries

• Fermilab Library -- an excellent starting point for information relating to high energy physics, astrophysics and engineering.
• NASA Astrophysics Data System -- The Digital Library for Physics, Astrophysics, and Instrumentation at Harvard University.
• Niels Bohr Archive -- collection features material by and related to the physicist, including documents related to the 1941 Niels Bohr-Werner Heisenberg meeting.
• Niels Bohr Library - American Institute of Physics Center for History of Physics -- resources include books, journals, archives and manuscripts, photographs, and interview tapes and transcripts documenting the history of 19th and 20th century physics and allied fields worldwide.
• SLAC Library -- provides information services to support Stanford Linear Accelerator Center research in high-energy and particle physics, and particle and synchrotron-radiation-based accelerator theory.
• Physics Encyclopedia -- internet resources
• Stanford University' Pysics Library
• UIUC-Physics-Astronomy Library
• University of Notre Dame - Chemistry-Physics Library

Societies

• American Institute of Physics
• American Physical Society
• Deutsche Physikalische Gesellschaft
• European Physical Society
• Institute of Physics
• International Astronomical Union
• Materials Research Society
• Optical Society of America
• Royal Astronomical Society