According to various sources, the number of stars in the Milky Way varies between 200 to 400 billion. On the other hand, the galaxies in the universe also vary around a trillion. Considering that there are about a trillion stars in each galaxy, there are 10,000,000,000,000,000,000,000,000 in the universe.
More than 2,000 years ago, the ancient Greek astronomer Hipparchus created the oldest known star catalog. According to Hipparchus, the stars are in 6 groups according to their brightness. 6th magnitude stars on the Hipparchus scale are the faintest. About 5 thousand stars can be observed with the naked eye in the Northern and Southern hemispheres.
Of course, these stars cannot be observed simultaneously. On clear skies, about half of them are visible. In large cities, due to street lighting and other sources, only the brightest are visible.
Who is the biggest star?
Perhaps many people think it is the Sun. Yes, the Sun is huge. Over a million Earths can fit in its area. But there are many other bigger stars than him.
The largest star known in the universe is UY Scuti.
UY Scuti is a pulsating variable hypergiant with a radius about 1700 times that of the Sun.
Where is the Milky Way moving?
In 1860, German astronomers at the Bonn Observatory first spotted this star, then called BD -12 5055. In the second observation, astronomers reported that the star grew brighter and gradually dimmed over a period of 740 days. Astronomers classify it as a pulsating variable star because it changes brightness over a period of time.
The star is located near the center of the Milky Way, about 9,500 light years from Earth. UY Scuti is a hypergiant star located in the constellation Squirrel, which can be observed at night in the summer season from the Northern Hemisphere. It can hardly be seen with the naked eye, but only with a professional telescope.
Hypergiants are larger than supergiants and giants and are among the rare stars that shine very brightly. It is at a great distance from the solar system. Its light takes about 5,100 years to travel from UY Scuti to Earth. This hypergiant star is located near the center of our galaxy, where a supermassive black hole known as Sagittarius A* is thought to lie. Hypergiants are larger than supergiants and giants and are among the rare stars that shine very brightly.
The Milky Way is more ancient than scientists thought
What is the size of the UY Scuti?
It is known that the radius of the Sun is 1.4 million km. The radius of UY Scuti is 1700 times that of the Sun. If we put UY Scuti in place of the Sun, it will swallow the first 5 planets of the Solar System – Mercury, Venus, Earth, Mars and Jupiter. Although gigantic in size, this star is not defined as a massive star by astronomers. The methods for calculating the mass of UY Scuti are not accurate enough. Astronomers estimate that it is about 10 times the size of the Sun.
Scientists believe that UY Scuti may go supernova in the future. This is the stage of a star when it gradually depletes the helium in its core. Because it cannot support its own mass, it explodes and becomes a supernova – one of the most beautiful events in the starry sky.
Even if this event did happen, it would not be observable with the naked eye from Earth.