V838 Monocerotis

V838 Monocerotis is a red giant star in the Monoceros constellation. It is famous for undergoing a sudden growth in size in the year 2002. When it happened, the star became 1,570 times bigger than the Sun. However, it shrunk in size - bringing its size to only 380 times bigger than the Sun. It is 20,000 times brighter than the Sun.