Algol: my favorite naked-eye object in the nocturnal sky
Published in Terschelling Diary 2008/1 in 2008
G. P. Können
The bright star Algol is the prominent exception of the seemingly never-changing  nocturnal sky, as it looses regularly no less than 70% of its brightness. The phenomenon lasts only a few hours. Events occur with intervals of three weeks. Surely one of the best objects in the celestial sky!