The Constellations

The majority of the common constellations date back to ancient times, but the exact list that we have today did not come into being until the early 20th century. Between 1922 and 1930, the International Astronomical Union (IAU) passed a series of resolutions which divided the celestial sphere into 88 defined areas with proper spellings and abbreviations. The constellations all fit on the celestial sphere like puzzle pieces on a giant 3-D spherical puzzle. Historically speaking, the word constellation was used in reference to a group of stars that represented an object of some sort (like the Big Dipper or Orion). Today, however, the word constellation officially is in reference to the "puzzle pieces" or divisions of the celestial sphere that contain these stars. The common star groups and shapes, like the big dipper, are now called asterisms.

Each constellation name has two forms: the nominative, for use when you're talking about the constellation itself, and the genitive, or possessive, which is used in star names. For instance, Hamal, the brightest star in the constellation Aries (nominative form), is also called Alpha Arietis (genitive form), meaning literally "the Alpha of Aries." This doesn't make life very easy for amateurs, but as the old saying goes, "it is what it is." We have included a chart below outlining the abbreviations and names of each of the 88 constellations.