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What Is Sirius in the Orion Constellation?

Orion is one of the most prominent constellations in the sky, visible to the naked eye in almost all parts of the world. The Orion constellation is named after The Hunter who was in love with Merope, one of the Seven Sisters of the Pleiades in Greek mythology. When extended southeastward, two of the stars in Orion's belt point to Sirius, which is the brightest star in the night sky -- almost twice as bright as the next brightest, Canopus.

Orion in Greek Mythology
- Because Merope wanted nothing to do with Orion, he wallowed in misery and mistakenly stepped on a scorpion that stung him. Seeing Orion in great pain, the Gods took pity and placed Orion in the sky as a constellation surrounded by his faithful dogs, Canis Major and Minor. Canis Major is otherwise known as Sirius. The Scorpion was placed on the other side of the firmament to protect Orion from ever being stung again. Orion is a useful navigational aid in locating other stars. The line of the belt extended northwestward points to Aldebaran and extended southeastward points to Sirius.
Sirius in Greek Mythology
- Often referred to as "The Dog Star," Sirius was Orion's faithful hunting dog who would not stop searching for Orion when he was plucked from Earth and placed into the night sky. To stop the dog's frantic, hysterical wandering, Artemis made Sirius a constellation right next to his master, Orion. The myth of how Orion was made into a constellation varies from the tale of the Scorpion to a tale of jealousy between gods, but the end result is always that Orion and his bright and faithful dog end up lighting the night sky together.
The Brightest Star
- Sirius is 8.6 light years away from Earth and radiates with a -1.47 magnitude, which essentially means that Sirius is 26 times as bright as the sun. The star Sirius is a white, class A hydrogen-fusing dwarf with a mass more than twice that of the sun and a temperature of 9880 Kelvin. Sirius takes 5.5 days to rotate and has an iron content almost double that of the Sun. In Ancient Egypt, the helical rising of Sirius marked the flooding of the Nile as well as the start of the calendar year.
Sirius and the Egyption Calendar
- Ancient Egypt had its own story for Sirius, involving Orion's sister and then wife, the goddess Isis. Whatever the story of Sirius, the fact remains that its transcendent luminosity impacted the Ancient Egyptian concept of time and the creation of the Ancient Egyptian calendar methodology. The first solar calendar consisted of 12 months, each with 30 days. The first day of this calendar year began with the helical rising of Sirius, or the Summer Solstice.

Astronomy