Algol is a star in the constellation of Perseus. It was catalogued by Ptolemy as the Lucida of the Gorgon. It is the model 'eclipsestar' varying in brightness over a two day period through the interpositions of a revolving dark satellite. The light-changes of Algol were noticed by Montanari in 1669 and methodically observed and explained by Goodricke in 1783. Research Algol
Argo-Navis is the southern constellation of the Ship, containing nine clusters, three nebulae, thirteen double and 540 single stars, of which about sixty-four are visible. Research Argo-Navis
Aries is a sign of the zodiac. Represented by the ram. It is a northern constellation of 156 stars, of which fifty are visible. It is the first of the twelve signs in the zodiac, which the sun enters at the vernalequinox, about the 21st of March. The first point in Aries is that where the equator cuts the ecliptic in the ascending node, and from which the right ascensions of heavenly bodies are reckoned on the equator, and their longitudes upon the ecliptic. Owing to the precession of the equinoxes the sign Aries no longer corresponds with the constellation Aries, which it did 2000 years ago. Research Aries
Cassiopeia is a conspicuous constellation in the northern hemisphere, situated next to Cepheus, and often called the Lady in her Chair. It contains fifty-five stars, five of which, arranged in the form of a 'W', are of the third magnitude. Research Cassiopeia
Castor is a star (Alpha Geminorum) of magnitude 1.6, the fainter star of the zodiacal constellationGemini, or the Twins. In 1719 it was discovered to be a visual binary star, with components of magnitudes 2.8 and 2.0 separated by 6 seconds of arc and revolving around each other in about 350 years. Each of these components has been found to be a spectroscopic binary. In addition, a faint companion, separated from the other two by 72 sec of arc, has been discovered. This star is also a spectroscopic binary, the two components of which revolve around each other in about one day. Hence, the entire system of the star Castor contains at least six stars. Its distance is about 45 light- years from the earth. Research Castor
Centaurus (the Centaur) is a southern constellation, which is visible chiefly south of the equator. The brightest star in this constellation, Alpha Centauri, is also the third brightest star in the sky. It is about 4.3 light-years from the earth and is the closest visible star to the earth's solar system. The star is actually a double star, with a third star, Proxima Centauri, revolving around the others. Research Centaurus
Abbreviations
Research Aldebaran
