Page:Illustrated Astronomy.pdf/80

 We have already said that there are other types of eclipses not related to the Moon and the Sun, but distant stars. 50 % of the stars are binary systems or more stars included.

The Sun, however, doesn’t have a stellar neighbor, but only planets. The binary stars can have different separations or orbits, and these are oriented randomly in the sky. Since there are many stars in our Galaxy, some binary stars orbit a plane very aligned with the Earth, so then, in a particular region of its orbit, a star passes in front of the other, blocking the brightness of the one in the back. These double stars are classified as eclipsing binary stars. A historical example is the star Algol, the second brighter star of the Perseus constellation, which name comes from the Arabic, and it means possessed star (from Ras Al-gul). When the Arabic astronomers saw the periodical change in the star brightness due to its eclipses, they understood that it was because of devilish powers given their world view of an immutable sky. 80 • • •