Scorpius - The Scorpion

Scorpius lies between Libra and Sagittarius. It appears as a looping curve of stars which forms the stinging tail of a scorpion. Scorpius lies in the western part of the Milky Way and contains many objects worth viewing. It is best seen from June to August.

History and Mythology

The scorpion has always been associated with darkness and death. It is feared because of its very painful sting, which is out of proportion to its small size. It hides under rocks, ready to sting when disturbed. Scorpius attacked the horses of Phaeton's chariot as he drove across the sky. The sting caused the horses to rear and run wild, throwing Phaeton to his death.

Scorpius is best known as the creature that killed the hunter Orion. Orion bragged that he could kill any animal in the world if he wanted to. When a goddess of the Earth heard this, she was so angry that she sent a scorpion to sting and kill Orion. When Orion died, the goddess Artemis placed him among the stars, where the scorpion is still stalking him. Luckily, they are on opposite sides of the sky. In autumn when Orion rises, Scorpius has already set, and when Scorpius rises in early summer, Orion has disappeared below the western horizon.

The Mayans called Scorpius the "sign of the death-god". Mars, the planet associated with violence and destruction, was believed to be born inside the bounds of Scorpius. If a comet appeared within the region of Scorpius, it meant there would be plague or locusts on the Earth. Dante refers to Scorpius as "that cold animal which with its tail doth smite the nations".

Notable Stars

The heart of Scorpius is the red giant star Antares, meaning "rival of Mars". It is the 15th brightest star in the sky. It is a red supergiant star about 550 light years away; its diameter measures 400 times that of the Sun, and it is 10,000 times brighter than the Sun. It is a semi-regular variable, with fluctuating magnitudes of 0.9 - 1.1. Antares is a well known double star, with a hot blue 5th-magnitude companion appearing 2.9 arcseconds away. Their orbital period is roughly 900 years.

Despite having the Bayer designation Lambda Scorpii, Shaula is the second brightest star in Scorpius, and the 24th brightest star in the night sky. Its traditional name comes from the Arabic phrase meaning "stinger", as it is found in the tail of the scorpion. It is actually a triple star system, though unresolvable in small telescopes, consisting of three hot blue stars 365 light years away. Upsilon Scorpii, or Lesath, is the other star making up the Scorpion's stinger; a hot blue star physically similar to Shaula, it is about 180 light years close.

The double star Beta Scorpii (Acrab or Graffias, meaning "scorpion" or "claws") is in the front part of the scorpion. It is much easier to split with small telescopes. It has blue-white components of magnitude of 2.6 and 4.9, separated by 14 arcseconds. Both are hot, massive, blue-white class B stars at least 10 times as massive os our Sun; both are expected to end their lives as supernova explosions.

Theta Scorpii, Sargas or Girtab, is the third brightest star in Scorpius at magnitude 1.9. It is a yellow giant shining from a distance of 270 light years.

Delta Scorpii, or Dschubba, is the middle of the three-star line that makes the head of the Scorpion. Dschubba means the "scorpion brain" or "forehead", and it is a blue white star of magnitude of 2.3. Originally fifth brightest in the constellation, it began to brighten in 2000, and became a 1st-magnitude star, the 2nd-brightest in the constellation, in 2003-2004. As of 2008, it remains in an erratic state near magnitude 2.1, about 0.2 magnitudes brighter than normal.

Clusters, Nebulae, and Galaxies

There are many globular clusters in Scorpius. M 4 can be seen with binoculars; and displays a central "bar" of 11th-magnitude stars in small telescopes. It is one of the closest globulars to the Sun, at 7,200 light years away.

Located halfway between Antares and Acrab is the globular cluster M 80. It is a compact globular cluster, and can be easily seen in a small telescope.

M 6 and M 7 are two bright open clusters which are naked eye objects. M 6 is known as the "Butterfly Cluster". This description comes from the arrangement of the stars into a butterfly-like figure with a body and two wings. It is located above the scorpion's tail. M 7, also known as Ptolemy's Cluster, is much larger and appears as a fuzzy spot against the Milky Way background. It appears twice the size of the moon, and was known to the Greek astronomer Ptolemy as early as 325 BC.

NGC 6231 is a bright open star cluster located near Zeta Scorpii with a total magnitude of 2.6. NGC 6231 is 5,900 light years away, and belongs to the Scorpius OB association of very young stars.

An interesting planetary nebula in Scorpius is the Bug Nebula, NGC 6302. It is an unusual object that has two protruding nebulous lobes.

For larger telescopes, two nebulae of interest are the Cat's Paw Nebula, NGC 6335, and the nearby NGC 6357, which also includes the open star cluster Pismis 24. These nebulae lie 5,500 and 8,000 light years away, respectively.