The Sirius Star is the brightest of all that can be seen in the earth’s night sky. Although it is not a record holder, its luminosity exceeds the Sun’s luminosity by only 25 times, while there are stars in the universe that have this parameter millions of times more incredible.
Sirius is not a single star but a binary star system. But only the brighter component, Sirius A, is visible from the ground, while component B can only be detected through a telescope. Astronomers learned that this system was double in the 19th century. Both stars revolve around their common centre of mass, making one revolution in about 50 years. Thus, Sirius became the first open binary system, and this discovery made a splash.
The brightest star in the sky could not go unnoticed, so it was given importance in various cultures. In ancient Egypt, it was considered the goddess of the sky and the coming of the new year by the name of Sopdet. The Sumerians considered Sirius the god of thunder Ninurta, and the indigenous New Zealanders of the Maori called him Rehua, worshipping him as the wisest creature in the universe.
Astronomers and astrophysicists are perplexed because some ancient scientists described Sirius as a red star, while in the visual spectrum, it looks blue. Theoretically, the luminary colour can change during the evolutionary processes taking place in the stellar depths, but several millennia is too short a time for this.
Of all the objects visible in the earth’s sky, Sirius is the seventh brightest. It is second only to the Sun, Moon, International Space Station, Venus, Jupiter, and Mars. At least when these objects are in positions suitable for observation.
Since the stars are by no means stationary, Sirius is also moving and in our direction. It is approaching the solar system at a speed of about 7.6 kilometres per second, and its apparent brightness will increase over time. But since it is displaced in space relative to us, after about 11,000 years, it will be impossible to see it from Europe.
These are one of the few stars that can be seen in the sky with the naked eye, even during the day. But the observation must be carried out in the absence of clouds and at a time when the Sun is low above the horizon. And, of course, you need to know precisely where to look.
No planets revolve around both components of the Sirius system since its age by cosmic standards is small, no more than 250,000,000 years. Moreover, component B, which is not visible from the earth, has already outlived its existence.
It was once a blue star, but it has already burned all its fuel, after which it turned into a white dwarf. This is one of the most massive white dwarfs; its mass is slightly more than the Sun’s mass, although, in volume, it is less than our star by about 1,000,000 times. Sirius B is very small; it is comparable in size to the earth.
About 25,700 years ago, Sirius was in the centre of the modern constellation of the Unicorn, although now it is part of the constellation Canis Major. In the future, this constellation will become an excellent reference point because it will shift towards the pole.
