• December 14, 2006

    Episode 72: A Light Echo

    Download this episode


    In 2002, an ordinary star in the night sky suddenly flashed to a brightness 600,000 times that of the Sun. No one knows why the eruption occurred, but since then, astronomers have monitored the star, known as V838 Monocerotis (V838 Mon), with the Hubble Space Telescope. An interesting nebula has formed and appears to be expanding around the central object. The nebula isn't really expanding though. The light from the intense brightening of the star is traveling through space, reflecting as it goes off the dust surrounding the star. This effect is called a "light echo." It's something like listening to a shout in the mountains as it reflects off of various surfaces.