Sirius

Sirius is the brightest star in the sky. It is at a distance of 9.5 light years from the Earth. It is also known as the Dog Star because it lies in the constellation of Canis Major, the Greater Dog. Sirius is actually a binary star and it is made of two stars that orbit around each other. Only the brighter of the two can be seen with the naked eye. Sirius was important in ancient Egypt before the calendars were developed. The appearance of Sirius coincided with the annual flooding of river Nile.