Here's why:
* Bayer designation: This system of naming stars uses Greek letters (alpha, beta, gamma, etc.) in order of apparent brightness within a constellation.
* Betelgeuse: While appearing brighter to the naked eye, Betelgeuse is actually a red supergiant, meaning it's actually less luminous than Rigel. However, due to historical reasons, it was designated as alpha Orionis.
* Rigel: Being a blue supergiant, Rigel is more luminous than Betelgeuse but appears less bright due to its distance from Earth. It was designated as beta Orionis because it was historically considered the second brightest star in the Orion constellation.
So, the "alpha" and "beta" in their names are just Bayer designations indicating their relative apparent brightness within the Orion constellation.
