Diagram 26

Star Designations

We’ve already devoted an entire diagram simply to let you study and learn the Greek letters, because they’re so important in astronomy. Now, it’s time to use them! As it turns out, when the brightest stars in each constellation were being named several hundred years ago, a naming system was invented that assigned the stars in each constellation a greek letter in descending order of brightness. This system gives us what is known as the Bayer Designation of each star.

Let’s use a famous constellation as an example. In Leo, the first five stars in order of brightness are named:

• Regulus
• Denebola
• Algieba
• Zosma
• Algenubi

These are their proper names, which they’ve had since antiquity, and are all of Arabic origin (except for Regulus, which was named by Copernicus in the 1600s). But we can also use Greek letters to name them. For example, Regulus is also called “Alpha Leonis”. Denebola is “Beta Leonis”, and so on down the line: Algieba is “Gamma Leonis”, Zosma is “Delta Leonis”, and Algenubi is “Epsilon Leonis”.

And there are other designations, as well. Regulus is known as α Leonis, but also as 32 Leonis, FK5 380, GCTP 2384.00, GJ 9316, SAO 98967, HD 87901, HIP 49669 and HR 3982 – as well as a couple other proper names. (But it’s even more complicated that that, because Regulus is actually a multiple star system, and each of the four component stars has its own set of designations!)

Select a constellation, and click on any star to see information about it!
(Make sure to read the instructions!)