SkyEye

Modern Constellations

The Dog-star and Aldebaran, pointing to the restless Pleiades, were half-way up the Southern sky, and between them hung Orion, which gorgeous constellation never burnt more vividly than now, as it soared forth above the rim of the landscape. Castor and Pollux with their quiet shine were almost on the meridian: the barren and gloomy Square of Pegasus was creeping round to the north-west; far away through the plantation Vega sparkled like a lamp suspended amid the leafless trees, and Cassiopeia’s chair stood daintily poised on the uppermost boughs.
— Thomas Hardy, "Far From the Madding Crowd", 1874

A constellation is a picture in the sky. Many of these familiar patterns of stars come to us from prehistoric times when humans first looked up into the night sky and tried to make sense of it. Others are of more recent origin, concocted when European explorers ventured far into the southern hemisphere. Today, the International Astronomical Union is the sole authority for assigning designations and names to celestial bodies, and in the early twenthieth century, they divided up the sky into 88 sections. These sections are irregular in shape and size as the IAU has tried to maintain ancient constellation boundaries as much as possible.

Extinct Constellations

Before the twentieth century, when the International Astronomical Union recognised 88 constellations and established their formal boundaries, constellations came and went, with astronomers and cartographers adding or renaming constellations with every new atlas published. Some honoured new-fangled inventions (the electricity generator, the hot air balloon), some flattered the important leaders of the day (Charles Ⅱ, George Ⅲ), some might even have been suggested as a joke (the pangolin?), but in the end, most of them didn't survive to the modern day.

The Christian Sky

There have been attempts to 'Christianise' the celestial sphere for as long as there has been a Christian religion. Perhaps the best known member of this movement is Julius Schiller, a German lawyer who based his 1627 star atlas Coelum stellatum Christianum on Johann Bayer's earlier work. In it Schiller replaced the zodiacal constellations with the twelve apostles, the northern constellations with New Testament figures and the southern constellations with Old Testament figures. However, the saints were no match for the pagans and the snappy new names never caught on. As John Hill (Urania, 1754) said in his description of Cygnus:

Schickard, Schiller, and their followers, that they may make [Cygnus], as well as the other constellations, preserve some part of the scripture history, call this the Cross, or the Cross of Christ, and St. Helena the hinder part of it. But these have few followers. It is obvious to all men what confusion must attend altering the figures of the constellations.

About the Charts

The online charts are drawn in colour on a dark background. Coloured circles of varying radius are used to represent stars. The larger the circle, the brighter the star. Binary and multiple star systems that appear as a single object to the naked eye are represented by their combined magnitude. The colours represent the spectral types (surface temperatures) of the stars, with blue being the hottest and red the coolest.

A selection of other interesting naked-eye objects are drawn in green. Galaxies are represented by ellipses, nebulae are triangles, open clusters are squares, globular clusters are circles and other objects of interest are denoted with a spiked circle. The positions of meteor shower radiants are shown with five splayed lines. The thick green lines represent the outlines of the constellations.

Star positions (epoch 2000), magnitudes and colours are taken from the Smithsonian Astrophysical Observatory Star Catalog. The limiting stellar magnitude is +6.5 but there is no limiting magnitude for other objects.

A listing of the image files may be found here.

Sources

For the two centuries between 1600 and 1800, celestial cartography flourished in Europe. This was its golden age. Atlases became more elaborate, more inclusive and more accurate. Perhaps the four star atlases that epitomised the age were Uranometria: omnium asterismorum continens schemata, nova methodo delineata, aereis laminis expressa (Johann Bayer, 1603), Firmamentum Sobiescianum, sive Uranographia (Johannes Hevelius, 1690), Atlas Coelestis (John Flamsteed, 1729) and Uranographia sive Astrorum Descriptio (Johann Elert Bode, 1801).

The etymologies of the names of the stars are outlined in (Un)common Star Names.