Light Echoes from V838 Mon . ... ESA , NASA Explanation: Nominated for most mysterious star in the Milky Way, V838 Monocerotis briefly became one of the brightest stars in our galaxy. ... But the nebula is actually a series of light echoes from formerly unseen shells of dust up to light-years in diameter. Previously ejected, the intricate shells progressively reflect light as it reaches them from V838 Mon's outbursts. ... NASA Web Site Statements, Warnings, and Disclaimers . ...