Ophiuchus

What is Ophiuchus?

Constellations· Summer evenings (N) · a large polygon north of Antares. Asclepius, the healer, grasping a serpent. The ecliptic runs through it, yet it is left out of the zodiac — the "thirteenth sign" the Sun crosses from late November to mid-December. Barnard's Star, the second-closest star system, lies here.

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bearing · altitude · rise time · best time tonight

Ophiuchus
Image: NowSky rendering (an illustration, not a photograph)· Wikipedia
Ophiuchus star lines
Star lines — the stars used and how they connect (NowSky)

Where Ophiuchus is in your sky right now: https://nowsky.org/solar/sky?sel=con:Ophiuchus — location and time set automatically, no login.

Stars of the figure

StarMagnitude
Rasalhague2.1
Sabik2.4

The 2 brightest of the 9 stars used in the figure (9 lines). Lower magnitude means brighter.

Deep-sky objects near this constellation

Lagoon Nebula M8nebulaTrifid Nebula M20nebulaGaia BH1black holeBarnard's StarstarM4open clusterKepler's Supernova Remnantnebula

Constellation basics

Seasonsummer evenings, June–August
Brightest starRasalhague (2.1)
How to findthe wide polygon between Vega and Antares
Area rank11th of 88

Figures are representative approximations. Source: compiled from NASA and IAU public data.

Frequently asked

When can I see Ophiuchus?
summer evenings, June–August.
How do I find Ophiuchus?
the wide polygon between Vega and Antares.
What is the brightest star in Ophiuchus?
Rasalhague, magnitude 2.1.
Where is Ophiuchus in the sky right now?
Open the sky view for your location and time and it shows the position in the sky right now.

The thirteenth-constellation fuss — a misunderstanding of 2016

In autumn 2016 news spread around the world that NASA had "added" Ophiuchus as a thirteenth constellation and changed everyone's horoscope. The actual source was an educational page for children explaining two old facts: that the Sun passes through Ophiuchus, and that constellations and astrological signs are different things. Astronomy had changed nothing and had no authority to, yet the fuss was large enough to require corrections.

The episode did spread awareness of the difference. The twelve signs divide the ecliptic into equal 30° segments, while the real constellation boundaries fixed in 1930 are uneven regions, so the Sun spends from 45 days in Virgo to 7 in Scorpius; the boundary of Ophiuchus simply covers 18 days of the ecliptic. The partition of the sky and the symbols of astrology are two systems that parted ways two thousand years ago.

The constellation in depth

Ophiuchus is Asclepius, the healer said to have raised the dead. When Hades complained that the underworld would empty, Zeus struck him down with a thunderbolt but honoured him with a place in the sky. The serpent he grips is a separate constellation, Serpens, and the serpent-entwined staff remains the emblem of medicine. The constellation spans the celestial equator and is visible from almost everywhere on Earth in the middle of the year.

Barnard's Star, a red dwarf six light-years away and the fastest-moving star in the sky, lies within its borders. Kepler's Supernova of 1604 exploded here — the last supernova in our galaxy seen with the naked eye. Because the constellation faces the galactic centre it is rich in globular clusters, and the dark Pipe Nebula hangs in silhouette against the Milky Way.

On summer evenings look between red Antares low in the south and Vega overhead for a broad polygon of unremarkable stars. Its northern corner, Rasalhague, sits beside Rasalgethi in Hercules. Set the Sky view to a July night to see the big figure directly above Antares, and switch deep-sky objects to level two to see Barnard's Star marked.

Related

Figures are representative approximations. Simulated positions use J2000 mean elements.