Betelgeuse is one of the largest known stars in the Milky Way galaxy. It is a red supergiant located in the constellation of Orion. Betelgeuse is a variable star, meaning its brightness changes over time. At its brightest, it is the ninth-brightest star in the night sky, and at its dimmest, it is the 21st-brightest. Betelgeuse is also one of the most massive stars known, with a mass about 20 times that of the Sun. It is also very large, with a diameter about 1,000 times that of the Sun. If Betelgeuse were placed at the center of our Solar System, its surface would extend beyond the orbit of Mars. Betelgeuse is expected to end its life as a supernova within the next 100,000 years. When this happens, it will be visible from Earth during the day and will be one of the brightest objects in the sky.