NGC 3372, known as the Great Nebula in Carina, is home to massive stars and evolving nebula. Eta Carina, shown above is the most energetic star in the nebula was one of the brightest stars in the sky in the 1830s, but then faded dramatically. The Carina Nebula spans over 300 light years and lies about 7000 light-years away in the constellation of Carina. Eta Carina might explode in a dramatic supernova within the next thousand years, and has even flared in brightness over just the past decade.
With more than 100 times the mass of the Sun, Eta Carina produces more than a million times as much light as the Sun. Only a few dozen stars of this size -in the 120 solar mass range- exist in the Milky Way and are assumed to approach the Eddington limit, where the pressure of their radiation is almost strong enough to counteract gravity.
Eta Carinae's had a massive eruption or supernova impostor event, which was observed around 1843. In a few years, Eta Carinae produced almost as much visible light as a supernova explosion, but it survived.
Image credit: NASA/ESA