On the evening of September 12, 2013, the moon shines above the constellation Scorpius and in front of Ophiuchus – the “overlooked” or “13th” constellation of the Zodiac. Once upon a time, the border between Scorpius and Ophiuchus was not a particularly well-defined section of sky, until the International Astronomers Union officially drew in the constellation borders in the 1930s.
Although you won’t see Ophiuchus on the horoscope page in the newspaper, the sun actually passes in front of this constellation from about November 30 to December 17. What’s more, the moon spends a few days within Ophiuchus’ borders each month.
Scorpius, the brighter of the two constellations, serves as the better stellar signpost. It’s much easier to visualize Scorpius as the Scorpion than Ophiuchus as the physician holding the serpent. Nonetheless – with the constellation borders placed as they are – the sun, moon and planets pass just north of Ophiuchus’ southern border, making it a member constellation of the Zodiac.
As seen from North America on September 12, the moon shines at the eastern edge of the constellation Ophiuchus. In the world’s Eastern Hemisphere – Europe, Africa, Asia, Australia and New Zealand – the moon appears farther west relative to the stars of Ophiuchus. You may need binoculars to see the star Sabik or the star Theta Ophiuchi (abbreviated “Theta” on sky chart) in tonight’s moonlit glare. Every year, the sun has a conjunction with Antares on or near December 1 and with Theta Ophiuchi on or near December 13.
Bottom line: On Thursday, September 12, 2013, the moon shines in front of Ophiuchus – the “overlooked” 13th constellation of the Zodiac.