Star Facts: Antares

Star Facts: Antares
Antares in Scorpius by © Alan Dyer/

Antares is a red supergiant star burning 10,000 times brighter than our own sun 550 light years away in the constellation of Scorpius. The star is the 16th brightest in the night sky, and can be seen in the Northern Hemisphere from late spring to early winter, where it shines with a variable magnitude of 0.9 to 1.8.

Quick Facts

Coordinates: RA 16h 29m 24s|Dec -26°25’55”
• Constellation: Scorpius.
Spectral Type: Red Supergiant (M1Ib)
• Distance to Earth: 600 light-years
• Magnitude: Varies between 0.9 -1.8
• Surface temp: 3,500K
• Mass: 15-18 solar masses.
• Radius: 735 million miles (880 solar radii)
• Luminosity: 10,000 sol
• Also known as: Alpha Scorpii, HR6134, and “The Heart of the Scorpion.”

Physical Properties

Antares is in actual fact a binary system consisting of the red supergiant Antares A, and the much smaller blue-green companion Antares B, which has a separation of about 574 AU from its companion, and cannot be seen without the use of a telescope. Antares A has a diameter 883 times that of our sun, and if it was centered in our own solar system would extend past Mars. It has a surface temperature of about 3,000C (5,400F), around half that of the Sun, with its low temperature accounting for its red color. Being a massive supergiant star (M1.5Iab-b) it burns its fuel much faster than low mass stars such as the Sun, and at roughly 12 million years old, it is already near the end of its life and is expected to go supernova within the next million years or so.


Star Facts: AntaresAncient star-gazers were familiar enough with the planets to be able to draw a clear distinction between the Mars (Ares), and the star which almost rivaled it in its ruddy color, Antares. In fact, the name “Antares” derives from the Greek for “The Rival of Mars”, or more literally, “Not Mars”, since the star lies in the ecliptic, and can easily be mistaken for the red planet.

Even further back, the fiery star enjoyed the full attention of Persian stargazers as long ago as 3000 BC, where it was named “Satevis” and associated with Selkit, the Scorpion Goddess. In ancient Arabia, it was known as “Kalb al Akrab”, which translates as the “Scorpion’s heart”, and is perhaps the first time it was referred to as such.

In some early Christian traditions, the star was known as one of the four “Arch-angel stars”, and it represented Oriel, the “Watcher of the West”. The other three archangel stars were Fomalhaut (Gabriel) as the ”Watcher of the South”, Regulus ( Raphael) as the “Watcher of the North”, and Aldebaran (Michael) as the “Watcher of the East”.


The mythology attached to Antares relates to the constellation of Scorpius as a whole, with the story recounting the tale of how Gaia, the Earth Goddess, sent a giant scorpion to sting Orion the Hunter as punishment for his boastful claim to be able to kill all living creatures on Earth. Scorpius fought and eventually killed Orion, so Gaia placed them both in the heavens, as a reminder for people to reign in their excessive pride. She placed the two constellation on opposite sides of the sky, though, and while Orion hunts in the winter sky, he flees when the scorpion rises in summer.

In Polynesia, the constellation has nothing whatever to do with venomous insects. There, the constellation is seen as giant fishhook that the demigod Maui used to snare and pull up land from the sea, that then became the Hawaiian Islands.