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LACERTA
The Lizard
Lacerta - Alexander Jamieson - 1822
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Lacerta is a small, visually unremarkable constellation, with not much to offer the casual observer. It was first identified as a constellation by Johannes Hevelius in 1687, and only he knows the reason why. Its zigzag pattern is similar to the nearby constellation Cassiopeia, which has given rise to its nickname of The Little Cassiopeia.
Lacerta has no named stars, and no Messier objects. It does have some open star clusters, the most significant being NGC 7243. It also contains a very small, very faint planetary nebula, IC 5217, discernible only in large telescopes.
The constellation Lacerta is also home to one of the most powerful energy sources in the Universe. Its name is BL Lacerta, discovered and catalogued in 1939 as a variable star, one of many found in our galaxy. But it didn't behave like other variable stars, and consequently was the subject of much study. It took almost half a century to determine that BL Lacertae was not a star at all, but the energy emitted by a super massive black hole at the center of a galaxy almost a billion light years away! It was a Quasar (Quasi-Stellar Object), the most powerful known object in the Universe.
Quasars are black holes that are overflowing. When black holes reach a certain size and age they begin to eject powerful jets of energy out into space that can be seen billions of light years away. But this Quasar had a spectrum that was different. Scientists decided this was because the jets of energy were pointed directly at us, and chose to name this type of Quasar a Blazar, of which BL Lacertae was the first.
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