Well, according to Wikipedia: Betelgeuse (Alpha Orionis) is a semiregular variable star located 427 light-years away [1]. It is the second brightest star in the constellation Orion, and the tenth brightest star in the night sky. Although it has the Bayer designation "alpha", it is not as bright as Rigel (Beta Orionis). It is a vertex of the Winter Triangle asterism.
So that explains it somewhat.