Scorpius Constellation: Brightest Star, Finding Its Shape, and Star Charts
A factual guide to the Scorpius constellation: its brightest star Antares, how to find its shape, and its place in star charts. Includes observing tips and a link to custom star maps.
What Is the Scorpius Constellation?
Scorpius is one of the 88 modern constellations and among the most recognizable in the southern sky. It lies between Libra to the west and Sagittarius to the east, and its shape resembles a scorpion with a curved tail. In Greek mythology, Scorpius is the scorpion that killed Orion, which is why the two constellations are placed on opposite sides of the sky. Scorpius is also a zodiac constellation, and the Sun passes through it from late November to early December.
The Brightest Star: Antares
Antares (Alpha Scorpii) is the brightest star in Scorpius and the 15th brightest star in the night sky. It is a red supergiant with an average apparent magnitude of about +1.06, though it is a slow irregular variable and can range from +0.6 to +1.6. Antares lies about 550 light-years from Earth and has a radius roughly 700 times that of the Sun. Its reddish color is due to its relatively cool surface temperature of about 3,500 K. The name Antares means "rival of Mars," referring to its similar hue to the planet.
Finding Scorpius in the Night Sky
Scorpius is best seen from the southern hemisphere and from mid-northern latitudes during summer. To find it:
- Look for a distinct J-shaped curve of stars. The "hook" is the scorpion's tail, and the "stinger" is marked by the stars Shaula and Lesath.
- Use Antares as your anchor. It is the bright reddish star at the heart of the scorpion.
- From the northern hemisphere, Scorpius hugs the southern horizon on summer evenings. From the southern hemisphere, it passes nearly overhead.
- Star-hop from nearby constellations: Libra is to the west, and Sagittarius is to the east.
A dark sky away from city lights will reveal the full shape, including the fainter stars that form the claws and legs.
Scorpius in Star Charts and Astronomy
On a star chart, Scorpius is plotted with its brightest stars connected to outline the scorpion. The constellation covers 497 square degrees, making it the 33rd largest constellation. It contains several deep-sky objects, including the Butterfly Cluster (M6) and the Ptolemy Cluster (M7), both visible to the naked eye under dark skies. The constellation also hosts the Scorpius-Centaurus Association, the nearest OB association to the Sun. Star charts typically mark Antares prominently and often include the constellation's boundaries as defined by the International Astronomical Union.