Author explains how Hubble's red shift of starlight spectra results from photon decay, proportional to traveled distance.

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.

Presents ideas about the rotation of the sun and planets.

A free online textbook on space physics.

Information mostly on the fourth dimension and theoretical physics.

Devoted to recent developments, discoveries, and theories in astronomy and astrophysics.

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.

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.

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.

An interactive Astrophysics textbook from Louisiana State University.

An explanation of the Titius-Bode Law of planetary spacing.

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).

Overview of the Titius-Bode Law.

University of Surrey abridged version of the book 'Astrophysics' , with many links to relevant material on astronomy, astrophysics and cosmology.

Interactive site for learning about astronomy and astrophysics.