Heavenly news: Sagittarius the centaur archer

A conversation with a frequent observatory visitor began innocently and pleasant enough but soon turned for the worse. I knew nothing about Sagittarius and by the end of the conversation I found myself having committed to write this article.

The story of Sagittarius is an amalgamation of many stories from different ancient civilizations. As far back as 1000 BC, the Sumerians speak of a creature with a tail of a “satyr.”

The Greeks later adopted the concept of the tailed creature and morphed him into, Crotus, the inventor of the bow and arrow. He was known to surround himself with the numerous goddesses of music and poetry — the muses. He would loudly applaud and stomp his feet in celebration of the music and in turn perform his marksmanship from atop a horse to the muses delight. Impressed with him, the muses convinced Zeus that he must be put in the heavens forever. Zeus obliged and today with an imaginative game of connect the dots, we find Crotus drawn as a centaur, half man and half horse, holding a bow and arrow pointed towards the heart of the nearby scorpion, the star Antares in Scorpius.

Sagittarius is found in the southern sky. From El Dorado county, look low in the early sky near the horizon. His horse half can be obscured by trees, low hills or even light pollution as it is very low on the horizon. His human half is higher above the horizon. It’s easiest to find if you look for the teapot asterism. His shoulders and arm make the handle. His head is the lid of the pot and the bow and arrow form the spout pouring to the west.

This region of sky is also brightly illuminated with the glow of the core of our galaxy, the Milky Way. This leads to a rich and diverse group of objects to view through telescopes.

Two objects are particularly noteworthy: the Lagoon Nebula and the Omega Nebula.

The Lagoon Nebula, or M8, is about 5,200 light-years away. Today we know this object is full of collapsing material forming new stars, providing nice patterns of bright and dark regions.

The Omega Nebula, M17, is another star-forming object about 5,000 light-years away with an open cluster of 35 young, hot and bright stars energizing nearby gas to glow.

Consider the following: at 5,000 light years away, the light has traveled for 5,000 years through the vacuum of space at a speed of 186,000 miles per second (6 trillion miles per year). Imagine that the light we observe from these objects left before the earliest record of the constellation itself and has travelled a total of 30 thousand trillion miles.

The light emitted from M22, a globular cluster of nearly 70 thousand stars, has even farther to travel, 10 thousand light-years away. It was noted by astronomers as early as 1665 as a nebulous object and later included in Charles Messier’s catalog in 1764. Individual stars were not resolved for another 30 years by William Herschel.

Globular clusters are dense groupings of old stars that orbit in the halo around the core of our Milky Way galaxy.

Last year these objects were a joy to view and should be even more so this year with the updated equipment at the Cameron Park Rotary Club Observatory. Being low in the sky, objects in Sagittarius are viewable through the community observatory scopes for a short period of time.

Take time to visit the observatory for a peek and tour of other constellations in the summer sky.

For information regarding location, current visiting hours and how to become a docent go to communityobservatory.com. Don’t forget to “Like” the community observatory on Facebook.