This week I take Sky & Telescope’s educational section and condense it. Their section is titled “What are Constellations?”.

Beginning with the word constellation, it comes from late Latin language (cōnstellātiō) and translates as “set of stars”. OK, that makes sense.

So, a constellation is a set of stars, and to be more thoroughly descriptive, a set of stars forming a recognizable pattern and given a name. We’re getting somewhere now, but the journey continues.

Going back, way back to our knuckle scraping ancestors, some of whom scratched pictures on cave walls, we know they saw star patterns. How do we know? Anthropologists have found scrawled star patterns on cave walls. Some appear to be Orion’s Belt, Taurus’ face (Hyades), and the Pleiades. While not all scientists agree with these interpretations, we know we humans have had a relationship with star patterns that goes way back.

The earliest universally accepted evidence of constellation drawings comes from Mesopotamia (Iraq), on clay tablets dating to 3000 BC. Sumerian, Babylonian, Chinese, ancient Greek, India, and later North and South American cultures’ writings about constellations were evolutionary developments that personified their cultures. Many of these cultures experienced “cross-fertilization” so to speak, over centuries, sharing or enforcing their knowledge and culture. Cultures in Australia and other isolated areas similarly tended to interpret star patterns based on local flora, fauna, male, female, and gods. Southern hemisphere constellations uniquely included those dark nebulae commonly seen south of the equator.

The earliest catalog of constellations comes from a consolidation of Sumerian, Babylonian, Egyptian, and Assyrian collections. From ancient Greece, Claudius Ptolemy’s Almagest perhaps serves us the first 48 constellations. That’s not bad considering world travel was not an easily available prospect in 350 BC. Fast forward a millennium or two and astronomers had come up with many and varying names for constellations. Something had to be done to eliminate the confusion! In 1930 we received an official catalog, presented at the International Astronomical Commission (IAU) 3 by Eugene Delporte.

Officially there are 88 constellations surrounding our Earth. Of course, if you don’t believe the IAU has final authority you can go ahead and create your own catalog, but good luck with that. No one but you will recognize or use it.

Well, it’s never as simple as it appears. Over the years many very recognizable star patterns have been given names, and have become well known, yet are not constellations. Patterns such as the Big Dipper, Little Dipper, the Pleiades, the Hyades, Northern Cross, and Southern Cross.  Most are part of a constellation – the Big Dipper is part of the constellation Ursa Major; the Northern Cross is part of Cygnus. Some are independent of constellations, such as the Pleiades. These patterns are termed Asterisms, to keep them separate from constellations. OK, that works!

What’s in the Sky?

November 25; after 8 pm; east: Winter constellations are rising above the horizon. So is brilliant Mars. It will be in Taurus the bull, to the left of bright Aldebaran.