Beneath the Scorpion’s tail

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By Mark Jankowski, Ingram Planetarium Director

The Scorpion is a superb sky object to find for a first timer or a beginner just learning to sky gaze. In fact, it is a superb object for anyone to look for in the sky because the Scorpion has oodles of science contained within its borders. What about outside of its borders? What is under the tail of the Scorpion? If you are thinking what I think you may be thinking, don’t be silly. Under the tail are several small constellations, and with the aid of the Scorpion, all are easy and fun to find. 

In mid-August, the Scorpion reaches its highest point in the sky during early evening hours. The trick of finding it is simply to look south as the stars appear. Now look above the trees, and as long as they are not too tall, you will see a prefect letter J formed by the stars. You may have to take a trip to the beach to get a glimpse under its tail. Here you will find one constellation formed long ago and two others formed not so long ago. 

The constellation formed long ago is Ara Centauri. This name sheds light on one of the myths about the star group that is the altar of the centaur Chiron. Chiron had a reputation for his wisdom. He was the one who taught man to use the stars by drawing lines to connect them. Another myth for the Ara is the gods used this altar as a place to form their alliance when they rose up against the Titans in the battle that placed Zeus in power. To find the small group, look where the J for the Scorpion just starts to hook. This group never gets all the way above our local horizon, and ancient star charts normally placed the altar upside down from our point of view. 

The two constellations formed not so long ago are Norma ET Regula and Tubus Astronomicus. These were both the works of Nicolas Louis de Lacaille. He formed them while he was surveying the southern sky in 1751-1752. Norma is half way down the right side of the letter J and Tubus Astronomicus is almost at the end of the J’s hook. Since both are of the more modern grouping of constellations, neither have a mythological story; however, there is some interesting history to share.

Norma ET Regula has a shorter name...just plain Norma. At first, the group was the Rule and Square. When the name was shortened to Norma, only one drafter’s tool was left, just the Square.

It is trivia time. The historian R.H. Allen mentioned in a book about star names that the group was Niveau. He was quoting the Flamsteed’s Star Atlas. Niveau means Level, not Square. Allen read the Atlas wrong, since the Level refers to the Southern Triangle. Because of this 200-year-old mistake, there is still confusion concerning Norma. It is the Square, not the Level. Read more in the book, “Ian Ridpath’s Star Tales.”

Tubus Astronomicus had a name change; the simpler name for it is Telescopium the Telescope. The Telescope has two stories. One labels it as a tribute to Galileo, the first person to make scientific observations with a telescope while staring up at the heavens. The second story is it is a tribute to the very long aerial telescope used by J.D. Cassini at Paris Observatory. 

For more information on telescopes, come to the Ingram Planetarium and watch “Two Pieces of Glass.” This planetarium dome show teaches about telescopes of all sorts and sizes. For help finding these constellations, download the sky chart from www.museumplanetarium.org.