Eta Carinae is a spectacular star. With a mass perhaps 100 times that of the Sun, it is very luminous, and barely stable. Even though it is 8,000 light years away, it became one of the brightest stars in the sky during an outburst about 150 years ago. Periodic but intensifying emission of X-rays from the star probably herald another outburst in January (although it is unlikely to be as violent). Observations of the coming outburst should, however, help us to determine whether Eta Carinae is a binary, and what causes it to emit X-rays.
