Stars

The stars are luminous elements which move above the surface of the Earth in a layer above the Sun, Moon and planets. The stars revolve above the Earth at the rate of the Sidereal Day, which is defined as the time between two consecutive transits of the First Point of Aries, which is about one rotation every 23.93 hours, or 4 minutes shorter than the Solar Day. The stars range in observable sizes, the largest being one tenth the diameter of the visible disk of the Moon. The stars come in various colors— red, green, purple, blue, orange—as well as various types, such as variable stars which appear to rapidly pulsate.

The study of the stars dates back thousands of years. Ancient astronomers were able to differentiate between stars and planets, as stars remain relatively fixed over the centuries while planets will move an appreciable amount during a comparatively short time. The ancients created the constellations and looked up to the stars as a calendar of the changing seasons, navigation, and sought to find associations with the position of the celestial bodies and events on Earth, in what is now known as Astrology.

Topics

 * Airy's Failure
 * Doppler Shift
 * Problems of the Galaxies
 * Southern Celestial Rotation
 * Stellar Parallax
 * Star Rotation
 * Star Size Illusion
 * Exoplanets

Cosmology

 * Cosmology Has Some Big Problems
 * Cosmological Principle