V838 Monocerotis is a star in the constellation Monoceros that is about 20,000 light years from our solar system.
Previously unknown, this star was seen to brighten on January 6, 2002, and went through a series of dimming and then rapidly brightening again.
Among other this, this created a light echo which was captured in images taken by the Hubble Space Telescope. According to Wikipedia,
While the photos appear to depict an expanding spherical shell of debris, they are actually formed by the illumination of an ever-expanding ellipsoid with the progenitor star at one focus and the observer at the other. Hence, despite appearances, the structures in these photos are actually concave toward the viewer.