Graphics by TheSky
August 22, 2016
JUPITER AND VENUS TO MERGE AS ONE
The planets: Early evening this week is a very productive time to observe the planets. We actually have two shows going on at the same time. First, the easy one: the red planet Mars and the ringed planet Saturn have been forming a pretty triangle with the star Antares, the red heart of the scorpion, for several months. This triangle has gradually moved across the evening sky and is now almost a straight line just to the west of due south. Mars is the brightest of the three and is distinctive due to its red color. Tonight Mars lies just slightly to the west/right and less than 2° above its namesake Antares. (The Greek name for Mars was Ares. Since this star was almost a match in color to Mars and almost as bright, the Greeks named it Antares or “Rival of Mars” to be a warning to mere mortals (muggles?) not to mistake it for Mars/Ares the god of war. While this meeting of a red planet and an almost identical red star is taking place, the beautiful Saturn lies 4.4° above Mars. The triangle we have been watching is now squashed almost into a line. In fact, due primarily to the motion of Mars, on Tuesday and Wednesday evenings these three will form a vertical line in our southern sky.
The second show would be even more spectacular were it not so low in the western twilight. On Saturday evening the two brightest planets, Venus and Jupiter, will be approximately 0.1° apart and will appear as one to the naked eye. They will set about 45 minutes after sunset so should be spotted very low in the west as the sky darkens. Mercury will lie about 5° below and to the left of the pair and can be located with some difficulty since it is much dimmer than Venus or Jupiter.
For the rest of the month, Mars is moving eastward and, thus, the pretty line of Saturn, Mars and Antares will once again be a triangle in the south. But, this time Mars will continue to move eastward and our triangle will dissolve. Low in the west Mercury and Jupiter will disappear into the sunset like cowboy heroes at the end of a Grade B western. (Oh, how I miss them!) But, the beautiful Venus will become our “Evening Star” well into the new year. Wish upon it, Pinocchio!
The stars: Last month we discussed the appearances of Sagittarius the archer and Scorpius the scorpion low in our southern skies on summer evenings. Standing above these two rather prominent constellations are two other constellations that, while not as prominent as Sagittarius and Scorpius, nevertheless cover more of the sky. These are the intertwined constellations of Ophiuchus the doctor and Serpens the serpent. Recall that the symbol for a doctor is the caduceus, the staff of Hermes or Mercury with serpents intertwined on it. As pictured on constellation maps Ophiuchus is usually seen holding the serpent in his hands with the head of the serpent, Serpens Caput, to the west and its tail, Serpens Cauda, to the east. Serpens is unique among the 88 classical Greek constellations. It is the only constellation in the sky that is divided by another. The head, Serpens Caput, and the tail, Serpens Cauda, appear on opposite sides of Ophiuchus but are traditionally considered to be a single constellation.
Ophiuchus was the doctor who treated Orion when he was stung by the scorpion; therefore, he is usually pictured with one foot on the back of the scorpion. Ophiuchus is a zodiac constellation. That’s right! You won’t find him in any horoscope because horoscopes are based on fictitious calculations originally derived from the positions of the sun along the zodiac in ancient times. In the past 3500 years or so the location of the sun’s path through the sky, the ecliptic, has changed due to precession, the wobble of the earth on its axis. In modern times the sun passes in front of the stars of Scorpius from November 23 only through the 29th; it then crosses the southern part of Ophiuchus from November 30 through December 17. So…if you were born in early December, your astronomical natal sign should be Ophiuchus and you are an Ophiuchid!
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PARI is a public not-for-profit public foundation established in 1998. Located in the Pisgah National Forest southwest of Asheville, NC, PARI offers STEM educational programs at all levels, from K-12 through post-graduate research. For more information about PARI and its programs, visit www.pari.edu.
For further information or questions about this Mountain Skies column, contact Dr. Bob Hayward at firstname.lastname@example.org. Graphics produced with TheSky Astronomical Software, Software Bisque.