Sirius is located in the constellation Alpha Canis Majoris. It is the brightest star in the night sky, with 22 times the luminosity of the sun. Canis major is at the heel of the constellation Orion. Sirius is bluish-green and very large, and is close to Earth (Distance in Light Years 8.60 ± 0.04, one of the nearest stars).
Sirius is also known as the Dog Star. Sirius is closest to the Earth in Summer, especially July and August. That's where the phrase "dog days of summer" came from.
Sirius has a smaller companion white dwarf star known as The Pup or Sirius B. The mass of Sirius is about twice that of the sun, while the mass of the companion star is slightly less than that of the sun.
Canis Major is usually seen as one of the two hunting dogs of the great hunter Orion (Sirius). The other dog is of course Canis Minor, the Lesser Dog. There are several versions of the myth of Orion and Sirius. Following is one Greek version:
Orion was madly in love with the daughter of King Oenopion of Chios, Metrope, but was never allowed to marry her. One day, while drunk, he did something horrible to Metrope, and her father asked Dionysis to curse him. Dionysis put him into a coma and then blinded him. When he awoke, he went to an Oracle, who told him he would get his sight back if he traveled east and let the rays of the sun strike his eyes. Orion did so, and after regaining his sight he moved to Crete. In Crete, the goddess of the moon, Artemis, fell in love with him, and was too distracted to remember to light up the sky with moonlight.
The god of the sun Apollo was jealous of Orion because of Artemis' love for him, and looked for a way to kill him. Apollo challenged Artemis to hit a speck far out in the ocean, teasing her about her archery skills. Apollo knew, although Artemis didn't, that the speck was really Orion swimming. Artemis killed him with a single arrow. When she realized it was Orion, she was overcome with guilt and placed him up in the heavens as a constellation. His faithful hunting dog, Sirius, would not stop searching hysterically for his master Orion, so Artemis placed him, the Dog Star, at Orion's heels.