NGC 6240 is a peculiar, butterfly- or lobster-shaped galaxy consisting of two smaller merging galaxies. It lies in the constellation of Ophiuchus, the Serpent Holder, some 400 million light-years away. Reuters

NASA's inclusion of a lesser-known, 13th Zodiac sign in an online children's publication earlier this year sent shockwaves among horoscope followers. The addition, a serpent-bearing sign known as Ophiuchus, reportedly joined the traditional dozen signs based on an error in the ancient Babylonian's astrological calculations. Zodiac enthusiasts with birthdays between Tuesday and Dec. 17 can call themselves Ophiuchans.

Like the other 12 signs of the Zodiac - Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius and Pisces, the seldom-recognized Ophiuchus is a constellation of stars with symbolic roots in ancient Greek mythology. Ophiuchus is often depicted as a muscular man holding a snake, an animal that came to symbolize wisdom and healing. One story says Ophiuchus is a depiction of Asklepios, child of sun god Apollo and a mortal mother. Another says it represents the ill-fated Laocoon who was killed by snakes at the behest of the ancient gods after he attempted to warn Troy about Greece's ploy to hide soldiers in a wooden horse in order to enter the city.

Ophiuchus is unique among the Zodiac signs as it is the only one associated with a real person. Asklepios was associated with the Ancient Egyptian physician Imhotep, who lived in the 27th Century BCE. Others astrologists make connections between Ophiuchus and Joseph from the biblical Book of Genesis.

While Ophiuchus may be new to mainstream horoscopes, its serpentine imagery has been correctly used correctly as the Rod of Asklepios and incorrectly as the Staff of Caduceus in medicine for quite some time. The former image's likely association with medicine likely stems from the treatment of a parasitic worm called Dracunculus medinensis, which doctors would remove from a patient's skin by making an incision and slowly winding the creature on a wooden stick.

Despite the controversy, a number of both astrologers and astronomers have rejected the change in the horoscope. Initial reports said the change was due to the wobble in the Earth's axis that has shifted the planet's position in relation to the sun throughout the 3,000 years since the Zodiac was conceived. Western astrologists, however, did in fact take this factor into account, according to astronomer Parke Kunkle. NASA also rejected any claims that its work has any bearing on astrology. Whether the traditional horoscope has changed or not, there has never been a proven relation between astrology and the human traits or terrestrial events.

Ophiuchans, according to astrologists, are natural truth-seekers and architects. They favor bright colors, are envied by many and are well-liked by authority and father figures. The lucky number associated with the sign is 12. For believers, Ophiuchus' entry affects the traditional dates of other Zodiac signs, which are now as follows:

Capricorn: Jan. 20 - Feb. 16

Aquarius: Feb. 16 – March 11

Pisces: March 11 – April 18

Aries: April 18 – May 13

Taurus: May 13 – June 21

Gemini: June 21 – July 20

Cancer: July 20 – Aug. 10

Leo: Aug. 10 – Sept. 16

Virgo: Sept. 16 – Oct. 30

Libra: Oct 30. – Nov. 23

Scorpio: Nov. 23 – Nov. 29

Ophiuchus: Nov. 29 – Dec. 17

Sagittarius: Dec. 17 – Jan. 20