Ophiuchus is a fairly large and rambling constellation, but it is one of the least well-known. Although Ophiuchus does touch the elliptic — the path that the sun appears to take through the sky — astrologers for centuries ignored it as part of the Zodiac. The constellation finally got some respect in 2011 when they added Ophiuchus as an astrological sign and realigned the Zodiac calendar.
Ophiuchus [Oaf-ih-YOU-kus] spans 948 square degrees in area. It can be found northwest of the center of the Milky Way. It is situated near the constellations Aquila, Serpens and Hercules and opposite Orion. The southern part lies between Scorpius to the west and Sagittarius to the east. The position of Ophiuchus is:
- Right Ascension: 17.18 hours
- Declination: -4.24 degrees
- Visible: between 80 degrees and -80 degrees
- Best viewed: In July around 9 p.m.
Notable stars and objects
Ophiuchus contains the second closest star to Earth — Barnard's Star — about 6 light-years away. The red dwarf star is a magnitude 9.5, making it a challenge to find with the naked eye.
Delineating the head of Ophiuchus, alpha Ophiuchi is an A-type giant. The star is also known by the name Rasalhague, meaning "Head of the Snake Charmer" in Arabic.
Two stars — eta Ophiuchi and zeta Ophiuchi, a hot blue giant that has a reddish appearance because of interstellar dust — mark the knees of Ophiuchus.
A red giant about 170 light-years distant, delta Ophiuchi (Yed Prior), a red giant 170 light-years distant, and epsilon Ophiuchi, a class G giant 108 light-years distant, form the snake charmer's left arm.
Ophiuchus is home to a number of star clusters, including M10, which is only 20,000 light-years from Earth. It has a magnitude of 6.6 and is a Shapley class VII cluster.
Ophiuchus also houses Kepler's Supernova, also known as Kepler's Star or Supernova 1604, as it was discovered by German astronomer Johannes Kepler in 1604. He tracked the supernova for a year and its remnants are still studied today as it was the most recent supernova to be observed with the naked eye.
As is the case with all of the Zodiac constellations, Ophiuchuswas recorded in the 2nd century by the Greek astronomer Ptolemy, and the name is Latin for "serpent bearer."
The snake is often associated with doctors, so Ophiuchus is often associated with healing images. The Romans associated the constellation with Asclepius, who learned the secret to immortality by watching one serpent treat another serpent with healing herbs. Zeus killed Asclepius with a lightning bolt because he didn't want everyone to be immortal, but later honored his good deeds by giving him a spot in the heavens.
The Babylonians associated the constellation with Nirah, a god who was sometimes depicted with a human upper body and legs that were serpents.
— Kim Ann Zimmermann, SPACE.com contributor