From the June 2008 issue

Have we ever seen any star as more than a point of light?

Ron Wilson, Amherst, New York
By | Published: June 1, 2008 | Last updated on May 18, 2023
Yes. In 1995, astronomers using the Hubble Space Telescope’s Faint Object Camera imaged the disk of Betelgeuse, Orion’s alpha star. Betelgeuse, a red supergiant, is about 600 times the Sun’s diameter and lies relatively nearby, just 425 light-years away. This combination gives Betelgeuse the largest apparent diameter of any star beyond the Sun. At optical wavelengths, Betelgeuse’s disk is about 0.055″ across. In the ultraviolet, though, the star’s extended UV-emitting chromosphere makes it 2.2…