Sirius is the brightest star system in Earth’s night sky. The name “Seirios”, means “glowing” or “scorcher”. What appears to be a single star to the naked eye is actually a binary system of the white dwarf. This system is formally known as Alpha Canis Majoris or alpha CMa.
Sirius in ancient Egypt
Sirius is recorded in the earliest astronomical records. It was known in ancient Egypt as “Sopdet”, which is written in Greek as “Sothis”. The Egyptians based their calendar on the heliacal rising of Sirius. This heliacal rising marked the flooding of the Nile in ancient Egypt and the “dog days” of summer for the ancient Greeks.
Sirius to Polynesians
To the Polynesians in the southern hemisphere, it marked winter. The heliacal rising of Sirius refers to the day it becomes visible just before sunrise after moving far away from the glare of the Sun.
Dogstar
Due to its prominent position in Canis Majoris (greater Dog) constellation, Sirius is often also referred to as the “Dogstar”.
Brightness
Sirius is the brightest star system in the night sky with almost twice the brightness of the second brightest star, Canopus. However, it is not as bright as the moon, Venus, or Jupiter. In fact, even Mars and Mercury appear brighter than Sirius at times.
Types of Sirius
The two stars of the Sirius system are termed Sirius A is a white main-sequence star with an estimated surface temperature of 9,940 K. It has an estimated mass that is twice that of the Sun. Sirius B is a star that has already evolved off the main sequence and transformed into a white dwarf. It has a mass almost equal to that of the Sun. It is one of the most massive white dwarfs known to us.
Red, blue, or white?
Greek astronomer Ptolemy had described the star of Sirius to be red in color around 1 CE and ancient China has been describing it as white since 4 CE. Astronomers believe that this star keeps changing its color. However, the reason is still being debated.
Compiled by: Madhurani Chavan