Scorpius

The Scorpion of summer

On summer evenings a long hook of bright stars curls along the southern horizon, with a red star at its heart. That is Scorpius, the Scorpion, one of the zodiac constellations the Sun passes through each year, in late November.

Unlike many star patterns, it truly looks like its animal. A short line of stars at the head makes the claws, Antares glows in the body, and a long tail of stars curves down and up again to a pair of bright stars at the stinger.

How to find it

Face south an hour or two after dark in late June or July. The brightest reddish star low in the south is Antares. If you are not sure it is not a planet, look for the three stars in a short vertical arc to its right (west): the head and claws.

From 40°N the whole Scorpion is visible, but the stinger only rises a few degrees above the horizon, so trees and city glow can hide it. The farther south you go, the higher it rides; from the Mediterranean coast it is much better placed than from northern Europe.

To the left (east) of the tail lies the Teapot of Sagittarius, which marks the direction of the center of the Milky Way. Arcturus and Spica, found from the Big Dipper's handle, lie to the west and higher up.

Main stars and their names

Antares means 'rival of Ares', the Greek name of Mars, because its red color and brightness resemble the planet's. It is a red supergiant, hundreds of times wider than the Sun, and its brightness varies slightly around magnitude 1. A small, hot companion star orbits it.

Shaula, in the stinger, comes from Arabic for 'raised' tail. Next to it, Lesath is said to mean 'sting'; the pair is sometimes called the Cat's Eyes. In the claws, Dschubba means 'forehead', and Acrab (also called Graffias) comes from al-aqrab, 'the scorpion'. That same Arabic word is the root of the Turkish name Akrep.

Many of the Scorpion's bright blue stars belong to the Scorpius–Centaurus association, the closest large group of young, massive stars to the Sun.

Deep-sky objects for binoculars and small telescopes

M4 lies just over 1 degree west of Antares. It is one of the nearest globular clusters, a ball of very old stars, about 7,200 light-years away. Binoculars show it as a round, soft glow; a small telescope begins to show individual stars.

M80, between Antares and the claw star Acrab, is a smaller, denser globular. Above the stinger, toward Sagittarius, M6 and M7 are bright open clusters. M6 is called the Butterfly Cluster for its shape. M7, the Ptolemy Cluster, was recorded by the astronomer Ptolemy about 1,900 years ago and is visible to the naked eye from a dark site.

Sweep slowly with binoculars from the tail toward Sagittarius and you cross dense star clouds and dark dust lanes of the inner Milky Way.

Mythology

In Greek myth Scorpius is the scorpion sent to kill Orion after the hunter's boasting, by Gaia in some versions or Artemis in others. The two were placed on opposite sides of the sky, so Orion sets in the west as the Scorpion rises in the east, still fleeing from it.

In Polynesia and among the Māori of New Zealand, the curved line of stars is the magic fishhook of the hero Maui, with which he pulled islands up from the sea. In Babylon, the stars were already a scorpion more than 3,000 years ago, and the Greeks later took over the picture.

Practical observing tips

Choose an observing spot with a clear, low southern horizon, such as a beach, a hilltop or an open field. From 40°N the best time is late June to mid-July, about two hours after sunset, when the Scorpion crosses the south.

Use a moonless night to see the Milky Way rising from the tail. Compare Antares with Mars when they are near each other in the sky; it happens every couple of years. Haze near the horizon dims stars, so pick a dry, clear night after a weather front passes.