If you could see the stars during the daytime, you’d see the sun shining in front of the border of the constellations Ophiuchus and Scorpius today. At about this time each year, the sun passes out of Scorpius to enter Ophiuchus. Like Scorpius, Ophiuchus is a constellation of the Zodiac, and every year the sun passes in front of Ophiuchus from about November 29 until December 18.
This year, in 2013, the sun enters the constellation Ophiuchus on November 29, at 6 p.m. CST in the central U.S. By Universal Time, that’s 0 hours (midnight) on November 30.
The ecliptic – which translates on our sky’s dome as the sun’s annual path in front of the background stars – actually passes through 13 constellations, although this is not commonly known. After all, when you read the horoscope in the daily newspaper or a monthly magazine, you see only 12 constellations, or signs, mentioned. No one ever claims to be an Ophiuchus. There are the 12 traditional zodiacal constellations. But the sun passes through Ophiuchus as surely as it does the others.
Today’s constellation boundaries were drawn out by the International Astronomical Union in the 1930s.
Look at the chart carefully, and you’ll see that the border between Ophiuchus and the constellation Scorpius for the most part lies just south of, or below, the ecliptic. In ancient times, the Ophuichus-Scorpius border was likely placed to the north of, or above, the ecliptic. Had the International Astronomical Union placed its constellation boundary where the ancients might have, the sun’s annual passing in front of Scorpius would be from about November 23 till December 18, not November 23 to November 29.
Sky chart of November 30 morning sky
Bottom line: As seen from Earth, the sun passes in front of the constellation Ophiuchus each year from about November 29 to December 18.