Object Analysis

V838 Monocerotis is a red variable star in the constellation Monoceros about 20,000 light-years from the Sun. It became famous in 2002 when it suffered a major outburst, momentarily becoming one of the most luminous stars in the Milky Way, roughly 600,000 times brighter than the Sun.

The most spectacular feature of this outburst was the "light echo." As the flash of light from the explosion expanded outward, it illuminated shells of dust that had been previously ejected by the star. This created the illusion of a nebula expanding faster than the speed of light, though it was merely the illumination moving across stationary dust.

The exact nature of the star and the cause of the outburst remain a mystery. Theories include a "mergeburst" (the collision of two stars), a helium flash, or the swallowing of giant planets. Hubble images of the light echo remain some of the most hauntingly beautiful in astronomy.