Betelgeuse

Red supergiant star in the constellation of Orion. It is the tenth-brightest star in the night sky, although its brightness varies. It is 1,100 million km/700 million mi across, about 800 times larger than the Sun, roughly the same size as the orbit of Mars. It is over 10,000 times as luminous as the Sun, and lies 310 light years from the Sun. Light takes 60 minutes to travel across the giant star. The name is a corruption of the Arabic word meaning ‘armpit’.

It was the first star whose angular diameter was measured with the Mount Wilson interferometer in 1920.