In 2002, the star V838 Monocerotis suddenly became 600,000 times brighter than the Sun. In fact, for a few weeks, it was the brightest object in our galaxy. Moreover, due to something known as a light echo illuminating its surrounding rings of gas, the star appeared to be expanding rapidly as well, making it one bizarre star. It has since died down, however, and astronomers are still not sure what caused the outburst.