Astronomy notes is an educational resource for introductory astronomy classes for undergraduates. This section discusses the Hubble constant, Olbers' Paradox, Hubble's Law, the cosmological principle and the perfect...

NASA furnishes a fabulous cosmology tutorial about the big bang theory and the evolution of the universe. Visitors can discover the foundation of the big bang theory (general relativity, the Cosmological Principle), the...

This site, created by John Walker of Formilab -- Switzerland, allows users to view the earth and moon, and daylight and night regions, from a wide range of viewpoints. These include from the sun, the moon, the earth, at...

The European Southern Observatory (ESO) is an intergovernmental organization comprised of 14 member countries. Its headquarters are in Germany, but they have three observatories in Chile as well. Their website is loaded...

This site is part of an online textbook, Fundamentals of Physical Geography by Michael Pidwirny, and provides an online chapter about the past, present, and future of the universe. Images illustrate the concepts...