Major stars in the night sky: Sirius

Brightest at night of Winter: Sirius (Canis Major α)

It is the brightest star at night during winter in north hemisphere (Apart from members of solar system). The magnitude of brightness is -1.45 which is 23 times of our sun. The main star is a blue colored star with the size of 1.7 times of our sun.Surface temperature of Sirius is very high - 10,000  ℃ which is twice as the sun.

Sirius has existed in the ancient history of Egypt, and its appearance is regarded to be the sign of Nile Delta flooding. So the star is regarded to be a symbol of fertility for Egyptians. For other cultures, it is a bit different. e.g. ancient Chinese regard Sirius as a star of disasters and bad interference. It symbolize alone and separate.

The name of Sirius is originated from Greece, meaning “burnt" or "hot weather”. It is because when Sirius is visible in early summer each year (also in northern hemisphere), usually it will be overlapped with the sun, and it is why it is regarded to be a source of heat.

In 1844, German astronomer Bessel discovered that Sirius is indeed a binary star (two stars revolving each other, instead of one single large star), according to the wavy revolving pattern of Sirius. The companion star is first observed by American astronomer A. Clark in 1862 with the use of a caliber 4.7M refracting telescope which is the largest at that time. The revolving cycle of The two stars is 49.9 years.

Mass of this companion star is similar to our sun but the diameter is much shorter (only 1/50), and it is the first white dwarf actually observed by astronomers.

Sirius is also called the Canis Major α and it has an important role in the ancient legends and myths of constellations. It is one of the stars of the Triangle in Winter (Le Triangle d'hiver, together with Betelgeuse and Procyon) and is probably the first star that most people come across in learning to view stars.

Because Sirius is so bright, basically no specific instruments will be required in observation. Of course, it is much better for viewing the stars in the rural areas away from cities. One more tip is, you should arrive at the site of observation at least 45 minutes in advance, so there is time for your eyes to adapt to the darker environment. You can bring a torch with you but please kindly be reminded not to use it too frequently, and there is no need for any sunglass or telescope.

Sirius - related legends

It is a legend spreaded among the Dogon people in Mali, Western Africa.
The tribes were traditional tribes of black people in Western Africa, believing to have been , their culture was not advanced in most circumstances, except in the category of knowledge in astronomy.It is somewhat impossible for people to have get such high level of astronomy, without even the most basic telescope for observing the universe. For example, they already know Sirius is indeed a binary stars (consists of two stars evolving each other), and Sirius β had a orbital period of around 50 years. This second star of Sirius was not discovered by scientists until late 19th centuries. How can a ancient, less developed tribes get such knowledge hundreds of years in advance?
In their local legend, the knowloedge from the star Sirius β was from a God named "Nuomo", who had come across with their ancestors long long time ago.Dogon people had an ancient picture, showing their God was travelling on a huge space (believed to be space craft) dragging a long long tail of flames. He landed from the sky, and taught various knowledge to the Dogon people.