The Electric Universe
- Physics knows four forces; 20th-century scientists were convinced that one of those, the electric force, played no macroscopic role in the Universe; site explains why that is incorrect.
- http://www.the-electric-universe.info/

The Astrophysics Spectator
- Articles published on this site cover current research in astronomy and astrophysics, describe our current understanding of astronomical phenomena, and comment on issues related to astronomical research.
- http://www.astrophysicsspectator.com/

THIS-Tuneable Heterodyne Infrared Spectrometer
- THIS - instrument pages for the Tuneable Heterodyne Infrared Spectrometer developed by the University of Cologne. THIS is a transportable receiver designed for atmospheric and astrophysical observations in the mid infrared spectral region (7-28 µm).
- http://www.ph1.uni-koeln.de/workgroups/astro_instrumentation/this/

Cambridge Relativity
- Beginner's guide to all the basic concepts of Astrophysics written by active scientists at Cambridge University, UK.
- http://www.damtp.cam.ac.uk/user/gr/public/

Encyclopedia of Astronomy and Astrophysics
- Comprehensive archive of explantory articles on all key Astrophysics topics, categorised and fully searchable; actively updated by the Institute of Physics.
- http://eaa.iop.org/

Gravity is Cool, or, Why our Universe is Hospitable to Life
- Text of the 1999 Oppenheimer lecture at UC Berkeley given by professor Freeman Dyson on the origin of life and other subjects.
- http://www.hartford-hwp.com/archives/20/035.html

Contents
- Accretion in astrophysics - active galactic nuclei, processes and dynamics.
- http://astron.berkeley.edu/~jrg/ay202/node1.html

The NASA Astrophysics Data System
- The Astrophysics Data System (ADS) is a NASA-funded project which maintains four bibliographic databases containing more than 4.0 million records: Astronomy and Astrophysics, Instrumentation, Physics and Geophysics, and preprints in Astronomy.
- http://adswww.harvard.edu/

ADAF Theory
- Accretion disk theory, mixing-length theory of convection, advection-dominated accretion flows.
- http://astrosun.tn.cornell.edu/us-rus/adaf.htm

AMASE - Astrophysics Multi-spectral Archive Search Engine
- An online astrophysics catalog developed using object-oriented database technology to help researchers locate multi-mission data in the NASA archives.
- http://adc.gsfc.nasa.gov/amase/

SIMBAD Astronomical Database
- The SIMBAD astronomical database provides basic data, cross-identifications and bibliography for astronomical objects outside the solar system. SIMBAD can be queried by object name, coordinates, other criteria (filters), and lists of objects.
- http://simbad.u-strasbg.fr/Simbad

Titius-Bode Law
- Overview of the Titius-Bode Law.
- http://milan.milanovic.org/math/english/titius/titius.html

The Titius-Bode Number Sequence Deciphered
- An explanation of the Titius-Bode Law of planetary spacing.
- http://users.telenet.be/TaoWeb/TitiusBode.htm

Grand Challenge Problems in Computational Astrophysics
- Research session at the Institute for Pure and Applied Mathematics (IPAM), Los Angeles, CA, USA; 7 March - 10 June 2005.
- http://www.ipam.ucla.edu/programs/pca2005/

Physics Topics - Teaching Notes
- Teaching notes on celestial mechanics, classical mechanics, and stellar atmospheres.
- http://orca.phys.uvic.ca/~tatum/

Famous Astrophysicists
- Profiles several prominent astrophysicists.
- http://www.famous-astrophysicists.com

Fermilab Theoretical Astrophysics Group
- Partially funded by a NASA Astrophysics Theory grant, find information about the group's past and future meetings.
- http://www-astro-theory.fnal.gov

Canadian Institute for Theoretical Astrophysics
- Nationally supported research centre. Find out about current research, upcoming seminars and job opportunities.
- http://www.cita.utoronto.ca

Hands-On Astrophysics
- Offers educational products that help students understand basic astronomy concepts.
- http://hoa.aavso.org

Red Shift by Photon Decay
- Author explains how Hubble's red shift of starlight spectra results from photon decay, proportional to traveled distance.
- http://members.chello.nl/~n.benschop

Olber's Paradox Solved
- A well know problem from astrophysics, Olber's paradox (Why is the night sky dark?), solved. As well as Newton's related Gravity paradox.
- http://home.wanadoo.nl/ronald.koster/olber.html

Living Reviews in Solar Physics
- A peer-refereed, solely online journal publishing invited reviews covering all areas of solar and heliospheric physics research. Published by the Max Planck Institute for Aeronomy, Katlenburg-Lindau, Germany.
- http://solarphysics.livingreviews.org

Hyperspace
- Site devoted to hyperspatial theories.
- http://artling.tripod.com

You Be the Astrophysicist
- Interactive site for learning about astronomy and astrophysics.
- http://imagine.gsfc.nasa.gov/YBA/yba-intro.html

Dyson Sphere
- A list of frequently asked questions with answers.
- http://www.nada.kth.se/~asa/dysonFAQ.html

Interdisciplinary Astrophysics Group
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- http://altamira.asu.cas.cz/

Above the Skies, An Exploration into Our Universe Through Animated Spectroscopy
- A description at the layman level about the applications of spectroscopy in the investigation of the Solar System, with interactive diagrams
- http://hea-www.harvard.edu/~efortin/thesis/html/index.shtml

Nuclear Astrophysics Data
- An area for providing nuclear data for astrophysics calculations, such as nucleosynthesis, stellar evolution, the Big Bang, and super-nova dynamics.
- http://t2.lanl.gov/data/astro/astro.html

Astrophysics
- E-Print archive since April of 1992.
- http://www.arxiv.org/archive/astro-ph

Solar System - Celestial Mechanics
- Presents ideas about the rotation of the sun and planets.
- http://www.surf2000.de/user/f-heeke/index.html

University of Surrey - Department of Physics (Research)
- University of Surrey abridged version of the book "Astrophysics" , with many links to relevant material on astronomy, astrophysics and cosmology.
- http://www.ph.surrey.ac.uk/astrophysics/index.html

Physics 208 - Introduction to Astrophysics
- Course offered via The Electronic University, an educational outreach server at the University of Oregon.
- http://zebu.uoregon.edu/~imamura/astro.208.html

Temporal Annex
- Information mostly on the fourth dimension and theoretical physics.
- http://temporal_science.tripod.com/

Space Physics Textbook
- A free online textbook on space physics.
- http://www.oulu.fi/~spaceweb/textbook/

Astrophysics and Astronomy
- Introductory essays on astrophysics and astronomy.
- http://www.hpwt.de/Astroe.htm

The Structure, Stability, and Dynamics of Self-Gravitating Systems
- An interactive Astrophysics textbook from Louisiana State University.
- http://www.phys.lsu.edu/astro/H_Book.current/H_Book.shtml

NASA Astrophysics Data System
- Search system for abstracts in astrophysics, planetary sciences and solar physics.
- http://adsabs.harvard.edu/

Network Generator
- Generates astrophysical reaction rates online using an extended database.
- http://www-astro.ulb.ac.be/Netgen/form.html

The Astrophysical Journal
- Devoted to recent developments, discoveries, and theories in astronomy and astrophysics.
- http://www.journals.uchicago.edu/ApJ/