It's a mystery

By Diane Cherry

As a newcomer to astronomy, one of the biggest hurdles is remembering the names of the objects in they sky. "erm - thingummy looks bright tonight' or ' I've got a really clear view of what'sit'. It's just not good enough is it? Here is my quick, idiots guide (I'm the idiot) to how stars, planets, constellations etc. got their names and a few of my favourites.

It's all Greek to me!

The ancient Greeks named 48 of the constellations from their mythology and many of our present day 88 constellations, have retained these names. Many names have been 'Latinised' e.g… 'Argo Navis' ' 'the ship Argo' came from the legend of Jason and the Argonauts. This large constellation has been split up into 4 present day constellations with Latin names ' (Carina, the keel ' Vela, the sail ' Puppis, the stern and Pyxis, the compass.) The brightest star in Carina is Canopus, named after the helmsman of the Greek King Menelaeus. Arcturus, the brightest star in Bo'tes, means 'bear keeper' in Greek and this star does seem to be following Ursa Major, the great bear, around the sky. However, only the brightest stars have been given proper names.

The Greek influence doesn't end there. The Greek alphabet is used to order the brightest stars in each constellation i.e. alpha ' is the brightest, beta ' the next brightest and so on. This system was first used by Johann Bayer in 1603 and you will find nowadays it is only used for the stars visible to Bayer and him instruments. Only 3000 stars appeared in his catalogue as a result. As technology has improved the number of stars we can see has increased. Fainter stars are assigned roman letters or Flamsteed numbers, a star numbering system drawn up by John Flamsteed in the 17 century.

When in Rome

The Greeks do not have it all their own way, the ancient Romans have also contributed quite a few of their legends to the night skies. All the planets in our solar (from the Latin for sun) system are named after roman gods and many of their satellites after demi-gods or mortals who lived with the gods. Other sources are used e.g. Shakespeare. Larger asteroids in the asteroid belt also draw their names from roman mythology.

As I explained stars are listed in order of brightness ' alpha, beta, gamma etc. and the name of the constellation goes after the letter. The constellation name is given in the Latin genitive form meaning 'of' so Sirius ' Greek for 'searing' or 'scorching' is also known as ' Canis Majoris = star alpha ' (brightest) of Canis Major (the great dog). This explains why the ending changes when you are talking about stars belonging to or 'of' that constellation. I knew 'O' grade Latin would come in handy if I waited long enough - - - !

Arabian Nights

Arabian astronomers kept the study of astronomy alive while Europe was in the dark ages and many star names are derived from the Arabic. However, just like the game of Chinese whispers, these names were copied wrongly, mis-spelt or changed to make them fit in with the roman alphabet and many of them would be unrecognisable to a speaker of modern Arabic. These names also give us a clue that some constellations were arranged a differently before 1930 when the final total of 88 was adopted by the International Astronomical Union. Zubenelgenubi and Zubeneschamali (try saying that through chattering teeth on a frosty night!) also known as ' and ' Librae (the two brightest stars of Libra), come from the Arabic for 'northern claw' and 'southern claw' because these stars once belonged to the neighbouring sign of Scorpius.

It gets Messier…

So much for stars, planets and constellations, but what about all the other objects that fill the night sky? Nebulae (Latin for 'clouds'), clusters and galaxies are termed deep sky objects and were first catalogued by a Frenchman Charles Messier. He catalogued 103 objects, although 7 others were added later. The NGC (New General Catalogue) is also a list of these objects followed by two IC's (Index Catalogues) as newer discoveries were made.

Important objects can be given names from various sources. Therefore M44 (Messier number 44), NGC2632, is also known as the Beehive Cluster or Praesepe, the manger. The two flanking stars are gamma ' Cancri and delta ' Cancri (the 3rd and 4th brightest stars of the constellation Cancer). These stars are commonly known as Asellus Borealis and Asellus Australis, the northern and southern donkeys which are feeding at the manger!

I hope this has been entertaining and I haven't made too many factual errors (I'm sure you'll let me know!).