Do you know what is the name the brightest star in the Earth’s night sky that can be seen without any telescope? Sure, it is Sirius. In translation from the Greek language it means «glowing».
LOCATION
It is very well visible when it is in the Nothern Hemisphere winter sky for the reason that its luminosity is much stronger in comparison with other stars. Moreover, it is located quite close to our planet — just 8,6 light years. The scientists say that if to place Sirius and the Sun near each other, the first would shine 20 times brighter than the Sun. The visual magnitude of Sirius is -1.46 and it means the star is really luminous because the less the number, the brighter the star.
So remember, every time you turn your head up and see the strongest light of a star, you can easily find Sirius. The best waymark is Orion belt consisting of three stars and down to the left there is the needed star, but more precise coordinates are: right ascension 06h 45m 08.9s, declination of -16 degrees 42 m 58 s.
NAME
This star is called «Dog Star» and the name is not accidental. Sirius goes to make up Canis Major constellation, from Latin it is translated as «the greater dog».
Look! It really resembles a dog!
HISTORY AND MYTHOLOGY
People noticed this cosmic body a long time ago: it is mentioned by the Greeks and Polynesians in some historic documents. The most known fact is that Egyptians followed the star intently and waited for it to appear in the sky as it was always a sign for them that the Nile river would rise and floods would happen. So it was a great help for people to know when they had to prepare to natural disaster, but floods did not only disrupted territories, they brought new soil as well. At that time Sirius was called Sothis.
You know, there is an expression of «dog days» signifying very hot and humid weather conditions. It is directly connected with this natural body. The Greeks had a belief that Sirius appearing in the sky at the same time as the Sun during July, August and some part of September, intensified humidity to the weather and people were prone to passivity. At the same time according to the observations, dogs became mad and behaved aggressively, which may add some sense to the idiomatic phrase.
Primary studies of star were done by Friedrich Wilhelm Bessel, a german astronomer, in 1844. He assumed and then discovered that Sirius was a binary star.
MODERN STUDIES
Due to progressive technologies and methods to explore the universe, the scientists succeeded to define the mass of Sirius B which is a companion star of Sirius. That was done by NASA’s Hubble Telescope which showed that Sirius B is a white dwarf that goes around Sirius each 50 years. Scientists’ curiousity that lasted for 140 years was satisfied: Sirius turned out to be smaller than the Earth with gravitational field 350 000 times more than the Earth’s and with the mass of 98% more than the Sun. Imagine, that one small cube of sugar weighting 3 grams on the Earth will have weight of 1,000 kilograms on Sirius.
Astronomers refer Sirius to an «A» type stars. Its temperature is much higher than the Sun’s. It generates energy by transforming hydrogen into helium by means of nuclear fusion. Imagine, that the temperature of the star equals to 9,940 kelvins that is 9,666°C.
They say that Sirius has been existing for more than 200 million years and in the beginning is was much bigger, but burned down. This theory could be truthful: ancient philosophers described the star as red that might mean that at that time is was different and larger than now.
Cosmos is definitely one of the most interesting fields to be discovered and the humanity will always try to know more facts about it. We, as ordinary people, can observe something of the universe without using special equipment and I think it is good to possess information what we see when we look at night sky.
See you in my next post!