Sirius – the brightest star in the night sky
Sirius is the brightest star in Earth’s night sky. Its apparent size is -1.46 m, and it is 8.6 light years away from us. The name of this star originates from the ancient Greek word Seirios, meaning glowing, red-hot.
It is one of the closest stars to us, and it is still getting closer to the Sun so that it is slowly losing its brightness and will continue to do so for the next 60,000 years.
After that, the distance between Sirius and the Solar System will begin to increase, but Sirius will still be the brightest star in Earth’s sky (excluding the Sun) for the next 210,000 years.
- Sirius is visible from late fall to early spring at latitudes below 75 degrees.
- Sirius is a binary star in the constellation Canis Major (the Big Dog).
Bessel
The German mathematician and astronomer Friedrich Bessel, while observing the movement of Sirius in 1843 and 1844, noticed small irregularities in its path, which led to the conclusion of the existence of a close but invisible companion that spoils this path with its gravity,
Eighteen years later, in 1862, Alvin Clark, an American astronomer and telescope constructor, really discovered a star of brightness 8.65 m near Sirius.
Later it was determined that this star moves along an elongated elliptical path around Sirius at a distance of 8.1 to 31.5 astronomical units.
When talking about the Sirius star system, it is called Sirius A, and its companion Sirius B. Sirius B is difficult to observe because of the blinding brightness of Sirius A.
However, with a good telescope and a special aperture, i.e. with a screen that blocks the light of a brighter star, it is possible to record it.
Sirius A has twice the mass of our Sun, while Sirius B is a very massive (for a dwarf) white dwarf that is 0.98 percent of the Sun’s mass.
In addition, that mass is packed into a volume roughly the size of our Earth. Such a large mass in a small diameter results in a huge density. The temperature on the surface of this star is 25,200 K.
Sirius B is now expiring, at the end of its stellar life because it has used up its nuclear fuel and the nuclear reactions that turn hydrogen into helium have stopped inside it. This star is still shining on.
The unusual story of the Dogon
Dogon is a country of Mali, Africa and home to the Dogon people. Today there are about 500 thousand of them. They live in rocky hills and on the slopes of mountains. They are mainly engaged in farming and hunting.
It is a very old people, known since ancient times. The main religious ritual of the Dogon is linked to the star Sirius. The Dogon believe that 3000 years ago their people were visited by amphibious beings from Sirius.
They entrusted their teachings about astronomy and Sirius to the French anthropologists who visited them in 1930. Among other things, they told them that there is an unusual star near Sirius, of enormous density and great mass.
Today we know that a star of high density and mass orbits Sirius – it is Sirius B.
But how could the Dogons from ancient times know about something that was only discovered by modern astronomy?
Today it is believed that the Dogon may have acquired knowledge of the star Sirius B from a group of astronomers who visited their territory to study the solar eclipse that occurred on April 16, 1893.
Sirius with us
The star Sirius can be seen in Europe from autumn to the beginning of spring, but since it lies below the celestial equator, it is always quite low above our horizon, and its light passes through the thick layers of the Earth’s atmosphere.
That is why we rarely see it in its full glory, and the vibrations of the air layers often cause slight changes in its color.
Ancient civilizations
The ancient Egyptians called the star Sirius Sothis. They believed that this star caused the floods of the Nile because the floods started with its appearance in the sky.
The seasonal appearance of Cirrus in the sky also marked the beginning of the new year.
By observing the arrival of Sirius, the Egyptians determined that a year has 365.25 days, i.e. that the year lasts a quarter of a day longer than previously believed.
This correction will be accepted much later by Caesar during the reform of the Roman calendar.
The Hellenes and Romans associated Sirius with Orion, the giant hunter whose constellation is nearby.
Since ancient times, Sirius has been called the Dog Star because it belongs to the constellation Canis Major. The constellation Canis Minor is also in the neighborhood. According to myth, both represent the hunting dogs of the hunter Orion.
Sirius has been called the Dog Star since ancient times, after the constellation in which it lies. In the old world, by the way, for a long time the hottest period of the summer was associated with the appearance of Sirius (in July and August), so the term “dog heat” has been preserved since then.
The “Dog Days” represent that sultry part of summer when dogs are easily maddened by the heat.
Sirius rising with the Sun in midsummer was believed to add its heat to the Sun, causing hot weather.
Sirius was also believed to affect humans and at the time of its appearance, we can become tormented by sluggishness and grumpiness.
