Betelgeuse, also designated Alpha Orionis, is a red supergiant star marking the shoulder of the constellation Orion, the Hunter. It is one of the largest and most luminous stars visible to the naked eye, shining with a distinct reddish hue. Betelgeuse is located approximately 642 light-years from Earth and varies in brightness and diameter due to its semi-regular variable nature. The star is nearing the end of its life and is expected to explode as a supernova within the next million years.