Piscis Australis, the Southern Fish, is an inconspicuous constellation far south of the Equator. Fomalhaut, its brightest star comes only 20 degrees above our horizon and must be looked for when it is near the meridian—about 9 o’clock P. M. in October.
APPENDIX H
COLORED STARS
You can easily notice that the stars differ in color. The following list gives the colors of a few of the brighter stars:
- White Stars: Sirius, Regulus, Vega.
- Blue Stars: Rigel and Spica.
- Red Stars: Aldebaran, Antares, and Betelgeux.
- Green Stars: B Librae.
- Yellow Stars: The Sun, Arcturus, and Capella.
APPENDIX I
DOUBLE STARS
When two stars are very close together they form what is called a double star, but double stars of which the two components are really near together in space and revolve around each other usually cannot be resolved, that is separated, into two stars without the aid of a telescope.
The North Star; Rigel, Castor; Procyon and Sirius, are all famous double stars.
APPENDIX J
VARIABLE STARS
A variable star is one whose brightness changes from time to time. A great many variable stars are known, but very few of them can be seen with the naked eye. There are different reasons given for a star varying in brightness. Our Sun is a variable star, and we are told that this is due to his spots. Another type of variation is perhaps produced by pulsations—the star periodically expanding and contracting. Again a double star formed of two bright stars which revolve round each other, as many double stars do, may eclipse one another, and this would cause a change in brightness. Here, then, are three good reasons for a star being variable.
The following are a few of the variables which can be seen with the naked eye: