On January 6, 2002, a previously unknown star was seen to brighten up in Monoceros, the Unicorn. Being a new variable star, it was designated V838 Monocerotis, the 838th variable star of Monoceros. The initial light curve resembled that of a nova, an eruption that occurs when enough hydrogen gas has accumulated on the surface of a white dwarf from its close binary companion. Therefore it was also designated Nova Monocerotis 2002. V838 Monocerotis reached maximum visual magnitude of 6.75 on February 6, 2002 after which it started to dim rapidly, as expected. However, in early March the star started to brighten again, this time mostly in infrared wavelengths. Yet another brightening in infrared occurred in early April after which the star returned to near its original brightness before the eruption, magnitude 15.6. The lightcurve produced by the eruption is unlike anything previously seen. The star brightened to about a million times solar luminosity ensuring that at the time of maximum V838 Monocerotis was one of the most luminous stars in the Milky Way galaxy.
(Source: NASA, ESA, Wikipedia)