For us, the Universe we live in is absolute and unlimited. We think it existed, exists and will always exist, although something inside us has never ceased to claim that everything has a beginning. There are a lot of the Universe origin theories, and the most famous one is probably the Big Bang Theory, according to which there was a great explosion of dense matter and energy 13 billion years ago, which resulted in what we nowadays call the Universe. Many scientists also believe that the Big Bang was just a cycle in an endless series of matter explosions, which has neither a beginning nor an end. Points of view differ, and the dispute lasts for centuries because of the attempts to understand and organize the stardate back to ancient times.
Over time the Universe was divided into galaxies, which nowadays are numbered in millions. More and more of them are being opened, so even the scientists cannot tell the exact number of the existing ones, although they managed to classify them into three main types: Spiral, Elliptical and Irregular. But whatever the type of Galaxy is, each one is composed of numerous stars, planets, asteroids, meteoroids intergalactic gas and black matter.
The Galaxy we have the pleasure to live in is called The Milky Way and refers to a type of spiral galaxy. It has a form of a flat disc with a large bulge in the middle. The Earth used to be considered the centre of our Galaxy for a very long time. After this the scientists made a mistaken assumption, stating that the centre of the Milky Way Galaxy was the Sun. In fact, the “heart” of the Galaxy located in its middle is a supermassive black hole, which is overwhelming in its size being three million times larger than the Sun.
These data have recently been obtained as a result of a constant 15-year long space study by scientists of the Galactic Centre and its ESO telescopes at the La Silla Paranal Observatory. The black hole situated in The Milky way does not come close to other cosmic bodies and has unique abilities to convert matter into energy and extrude material at a speed close to the speed of light. By far there have not been detected any objects in the entire universe with such incredible properties.
The place occupied by our Sun among the stars in the Galaxy is fairly modest: it is an average one among billions of ordinary stars and it is twice farther from the centre of the Galaxy than from its edge. However, for us, the Sun will always remain the most beautiful and important star, the only one in its system, which served as a name for the whole system. The Solar System consists of eight planets, each located on its own distances, and the farther the planet from the Sun is, the longer its orbit is. Each planet has its own natural satellites, and there may be either one of them, as in the Earth’s case, for example, or ten and more, as some giant planets have. There are two exceptions to this system though – Mercury and Venus have no moons.
Our Sun is very bright and glittering, and its surface recalls a boiling gas mixture with a temperature of about 9941 °F. It consists of 74% of hydrogen, 24% of helium and the remaining 2% include a small amount of iron and nickel. In other words, the entire Solar System is composed mostly of hydrogen. Its structure, of course, includes other substances, but their percentage is only 0.1%. The Sun is heavier than all the planets, so it has a huge gravitational force that keeps the planets in their orbits.
The Earth is the third planet in The Solar System and is about 150 million miles away, while the light emitted by the Sun is still able to cover this distance in just eight minutes. The Sun mass is bigger than the Earth’s approximately 330 thousand times and larger in 109 times.
Although these numbers may seem huge to us, there exist much bigger stars than the Sun, such as Sirius, Betelgeuse and Antares, though they are incredibly far away. But their size and brightness give us a chance to distinguish them in the night sky, among other 6000 stars visible to the naked man’s eye on a clear night sky.
Size is not the only difference stars have in common. Colour is another category that varies depending on the temperature and can fluctuate from red to white or blue. The coolest stars are represented by the red colour, while the blue one is an indication of the hottest stars, which surface temperatures can rise above 12000° F.
There are also many similarities between the stars. They are all born from a cloud of cold molecular hydrogen, which is gravitationally compressed at its first stage. When the cloud is fragmented, many of its parts are generated in separate stars. Material is shaped in the form close to a ball and constantly undergoes the influence of its own gravity. Meanwhile, the temperature in its centre goes higher and higher until it runs up to the level necessary to ignite nuclear fusion.
If one bothered to collect all stars together and compare their size and structure in order to find out which ones are the most popular, the biggest group would definitely consist of red dwarfs. They have less than 50% of the mass of the Sun and can weigh even 7.5 per cent less.
Death is another common event in stars’ lives. They pass away gradually (billions of years) because of the failure of nuclear fuel. Hydrogen is converted to helium, which is concentrated in the nucleus, and helium reactions occur only on the surface of the star. The core of the star begins to cool and the stars collapse inside. Unfortunately, according to scientists, our Sun will also burn out completely in 6 billion years.
All these facts and other data about the stars and space are available to us mostly thanks to telescopes. Today, there are seven complexes that have telescopes with a mirror diameter of more than eight meters. The largest of them is located in the Atacama Large Millimeter Research Center Array in Chile. The biggest telescope in the world is made up of 66 radio telescopes with diameters from seven to twelve meters. They are all combined into a single device that has an incredible resolution and can capture objects in the depths of the early Universe, where the galaxies were formed billions of years ago.
In the nearest future, we expect to see the construction and introduction of telescope tools with a primary mirror diameter of 30 and 39 meters. So, the biggest star records are still to be set. Who knows what other secrets our Universe will tell us and whether all her secrets can be revealed at all. On the other hand, the most important thing is what we want to know and what we actually need: to disclose all mysteries, classify all-stars, systems and galaxies and mark the accurate space borders or fascinate the very process of finding out new information about how our Universe works.