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

AstroEngine - Space science blog by Dr Ian O'Neill discussing astrophysics concepts in an informed yet informal way.

The Astrophysical Journal - Devoted to recent developments, discoveries, and theories in astronomy and astrophysics.

Astrophysics - A short introduction to astrophysics with associated articles on a number of topics.

Astrophysics - Wikipedia article on this branch of astronomy that deals with the physics of the universe, including the physical properties of celestial objects and the interstellar medium, as well as their interactions.

Astrophysics - E-Print archive since April of 1992.

Astrophysics and Astronomy - Introductory essays on astrophysics and astronomy.

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.

Cambridge Relativity - Beginner's guide to all the basic concepts of Astrophysics written by active scientists at Cambridge University, UK.

Canadian Institute for Theoretical Astrophysics - Nationally supported research centre. Find out about current research, upcoming seminars and job opportunities.

Cause of the Spectral Characteristics of Quasars - Hypothesis which attempts to explain the characteristics of quasi-stellar objects as optical illusions created by gravitational lensing and other phenomena.

Dyson Sphere - A list of frequently asked questions with answers.

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.

Encyclopedia of Astronomy and Astrophysics - Comprehensive archive of explanatory articles on all key Astrophysics topics, categorised and fully searchable; actively updated by the Institute of Physics.

Encyclopedia of Astrophysics - A free peer-reviewed online publication written by scholars from around the world.

Fermilab Theoretical Astrophysics Group - Partially funded by a NASA Astrophysics Theory grant, find information about the group's past and future meetings.

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.

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.

Hands-On Astrophysics - Offers educational products that help students understand basic astronomy concepts.

High Energy Astrophysics Group - Astronomical Institute, Ondrejov. Focuses on the research of cosmic objects in X-ray and gamma spectra region. General information, projects and workshops.

Hubble Red Shift and Quantum Evolution - Michael Lewis provides an equation describing the Hubble red shift light decay curve using existing mathematics.

Hyperspace - Site devoted to hyperspatial theories.

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.

NASA Astrophysics Data System - Search system for abstracts in astrophysics, planetary sciences and solar physics.

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.

Network Generator - Generates astrophysical reaction rates online using an extended database.

Nuclear Astrophysics Data - An area for providing nuclear data for astrophysics calculations, such as nucleosynthesis, stellar evolution, the Big Bang, and super-nova dynamics.

Olber's Paradox - A well know problem from astrophysics, Olber's paradox (Why is the night sky dark?), solved. As well as Newton's related Gravity paradox.

Physics Topics - Teaching Notes - Teaching notes on celestial mechanics, classical mechanics, and stellar atmospheres.

Red Shift by Photon Decay - Author explains how Hubble's red shift of starlight spectra results from photon decay, proportional to traveled distance.

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.

Smithsonian Astrophysical Observatory - A research institute of the Smithsonian Institution headquartered in Cambridge, MA, where it is joined with the Harvard College Observatory (HCO) to form the Harvard-Smithsonian Center for Astrophysics (CfA).

Space Physics Textbook - A free online textbook on space physics.

The Structure, Stability, and Dynamics of Self-Gravitating Systems - An interactive Astrophysics textbook from Louisiana State University.

Temporal Annex - Information mostly on the fourth dimension and theoretical physics.

9th Annual International Astrophysics Conference - To be held March 14 - 19, 2010 at the Center for Space Plasma and Aeronomic Research (CSPAR) at The University of Alabama.

Titius-Bode Law - Overview of the Titius-Bode Law.

The Titius-Bode Number Sequence Deciphered - Compares earth orbit to other planets using the Astronomical Unit as a measurement.

Tuneable Heterodyne Infrared Spectrometer - THIS - Instrument pages for the transportable receiver designed for atmospheric and astrophysical observations in the mid infrared spectral region (7-28 µm). Developed by the University of Cologne.

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.

Virtual Institute of Astrophysics - VIA provides lectures and forums where scientists from around the world can communicate and discuss problems and ideas in astroparticle physics.

You Be the Astrophysicist - Interactive site for learning about astronomy and astrophysics.