Use a telescope to track the stars. Illustration: IT. Stay away from lights when observing the sky When using a telescope to observe the sky, determine for yourself reasonable objects and choose the right time and place to observe them. Strong light is the enemy of the astronomical observer. Therefore, stay away from city lights. If you are in the city, you can go to the quiet suburbs if possible. Otherwise, you should choose high positions and have a wide viewing angle to limit the effects of light pollution. Which objects are best for you to observe with amateur telescopes? Many young people after completing the telescope with their own hands feel disappointed. Because you have too much hope for a dream glasses without taking into account the reality factor. Remember, even the glasses that cost thousands of dollars that you order from the world’s leading manufacturers cannot allow you to see the colors shown in the photos taken on Google. Also, pay attention only to the brightest and most observable subjects. Which objects are the brightest? Except for the Moon, readers with basic knowledge of astronomy will think of Venus, Jupiter, Mars or Sirius – the brightest star after the planets in the system. However, Venus is not a good object to observe even though it is very bright. All you see is a yellow halo due to its thick and toxic atmosphere. Stars like Sirius, Canopus, although many times brighter than that, they are just distant balloons. It is not a reasonable target for observation through amateur optical telescopes. The best observed objects are the Moon first, followed by Jupiter, Saturn, Mars and a few galaxies, remarkable nebula. Don’t Observe When The Moon Is Full To observe the Moon, adjust the position of the eyepiece accordingly and aim at the vicinity of the semi-dark area during the nights between the 6th, 7th and 11th of the 12th lunar month. The full moon is a bad subject because it is so bright that it will obscure the craters and valleys you can see. You can solve this with a thin layer of glass called a moon filter, which will reduce the light of the Moon as it reaches your face. With industrial-grade telescopes, most have this. As for the homemade glasses, you can also design it yourself using a glass or a piece of blue plastic but still clear enough to see through it. Even so, the Moon should not be observed on full moon nights. Because in addition to it covering itself, it also obscures other attractive objects of observation, except, of course, on full moon days when the lunar eclipse occurs. You should have a map of the visible part of the Moon to compare when observing. These maps are now easy to find on the Internet and simply print out with any black and white printer. To observe the planets, it is best to choose the right time for good results. Planets have a different period than Earth, so they do not have a stable position like the distant star background. The easiest way is to use computer software to check the positions of the planets, or you can use free software downloaded at www.stellarium.org. Do not forget to set the exact location of the user and when you want to observe. It is advisable to choose days that are not full moons because the planets are in relatively high positions. Jupiter is the most observable object through amateur telescopes. Push your eyepiece a little deeper than when looking at the Moon and try to orient the lens because it will disappear instantly if you don’t keep your gaze exactly. Although it is not possible to see the colors as clearly as in the photos online that have been taken with exposure techniques, and through equipment thousands of times more modern than the amateur glasses you own, the colors Basic with brown lines, dark yellow is what you will see, and moreover the 4 Galilean satellites of this planet. Saturn is like Jupiter, just determine the right direction and fix the glass and you will easily observe it. The most interesting thing to look at this planet is its ring. However, it won’t be as colorful as you’re used to seeing in the photos, both the planet and the ring appear pale yellow. Next in the Solar System is Mars. But observing this planet is not very interesting because all you see is a faint red and maybe some black patches with faint ice caps at the poles if the telescope is relatively good. Anyway, this is the only planet in the Solar System that we can see some of its surface through amateur telescopes. One type of object that is very interesting to observe with amateur telescopes or, more neatly, tubes are bright galaxies and nebulae. Remember to push your eyepiece even further towards the objective so that you can observe the celestial bodies at infinity. The first notable is the Andromeda Galaxy (M31), a spiral galaxy. At a distance of nearly 3 million light-years, it emits light strong enough to be seen with the naked eye. Even with a small binocular you can see a band of light that seems to be a combination of countless small bright dots when directed towards it. What you see is billions and billions of suns like our own. Next is the Pleiades star cluster (M45), also known as the stellar group. It is also easy to recognize with the naked eye, it is a small group of 7 brightest stars located right in the constellation Taurus. Through binoculars or small telescopes, it can be clearly seen that it is a blue star cluster with many stars, including 7 brightest stars visible to the naked eye, so it is called the Seven Stars. This is an open cluster in the milky Way located 400 light-years from Earth. Another member you should look out for is the Orion Nebula (M42), an emission nebula with the same galaxy about 1,350 light-years from Earth. The Orion Nebula, although visible to the naked eye, is quite faint.

Exploring the stars is man’s way to the universe. Some people think that each star represents a destiny, others say that the stars are small angels tasked with lighting up the night. Today, science has been able to give us a more precise answer. What is a star? Stars are all celestial bodies that are capable of emitting their own light. All of them are giant air spheres. They are tens to hundreds of thousands of times more massive than Earth. Only thanks to such a large mass can they create their own light. An object to be able to emit its own light needs to have a mass of at least 70 times the mass of Jupiter – the largest planet in the Solar System, that is, about 7% of the mass of the Sun. Why do we see the stars? The stars in the sky have always been a mystery to the human imagination. Our Earth has a mass of about 6x1024kg (6 million billion billion tons). The Sun is 330,000 times heavier than the Earth. That is, a star with a mass of 7% of the mass of the Sun would be about 23,000 times heavier than the Earth. Every object has a gravitational force that directs the center of it to its heart. Normally no one notices but we ourselves are always attracted to our own. Because each part of the body is attracted to each other and the sum of them all form a gravitational force directed towards a center of mass in our body (the center of gravity of the object). The table, the chair, the Earth, are always gravitating to itself by a force called centripetal gravity. But why doesn’t it all burn brightly? That’s because the mass of the objects we come into contact with every day just can’t afford that. Because gravity is a force proportional to mass, gravity in everyday objects is so small that they don’t cause any significant effects. With very large objects such as planets, Earth, gravity is also negligible because it creates a clear attraction that pulls everything towards it. For example, when you jump high, you will fall very quickly because of the pull from the Earth. As for the aforementioned massive objects (tens of thousands of times heavier than the Earth), the great gravity makes the pressure at the center of the celestial body very high, this pressure provides a great acceleration for the celestial bodies. gaseous atoms (mostly hydrogen). They collide strongly with each other at high velocities, breaking the electron shells, separating electrons from the atomic nucleus. At the core of the star is no longer ordinary gas but a state of chaotically moving nuclei and electrons. This state is called plasma. In the plasma state, the hydrogen nuclei have a chance to collide directly with each other at high velocities, which causes what we call fusion reactions, fusing hydrogen nuclei into heavy hydrogen and finally is the helium nucleus. This reaction is known on Earth in hydrogen bombs – bombs capable of releasing thousands of times more energy than atomic bombs of the same mass. The fusion reaction at the core of a star releases a lot of energy in the form of radiation, some of which is visible light. This radiation is transferred to the star’s surface and causes the star to glow. Stars are composed mainly of hydrogen (over 70%), with a large part helium remaining, and an insignificant fraction of heavier gases. The surface temperature of a star is usually in the range of 3,000 to 50,000K, and the temperature at the center is in the range of several million to several tens of millions of K. It can be as high as 100 million K for red giants and several billion K. with red supergiant stars. Star classification Graphic image. By mass, stars are divided into two types, dwarfs and giants. Today, modern division is based on spectral charts. In which, the star with the obtained spectrum of which position on the chart will be determined to belong to which group with specific characteristics of mass and temperature. The most widely used spectrogram today is the Hertzsprung-Russell chart. This graph represents the luminosity, size, and temperature of any star when its spectrum is obtained. According to temperature, the chart is divided into 7 levels with the symbols O, B, A, F, G, K, M respectively. In which, the star closer to O is hotter and closer to M is cold. Each level itself is divided into several sub-levels. Through the chart, it can be seen that most of the stars in the universe are concentrated in the main sequence of the chart. This sequence is a sequence of dwarfs and subgiant stars. Our sun is also on this sequence. It is located in the G group, has the detailed spectral designation G2V (yellow dwarf/Yellow dwarf). Below the sequence are groups of white dwarfs, and above are giants and supergiant, supergiant stars. Star evolution All stars form from large clouds of dust and gas called protostar nebulae. Due to gravity they gather together and shrink until they form a dense mass. As we all know, all objects that carry mass carry gravity. The same object itself also has a force of attraction between different parts of it. However, the gravitational force between small masses is negligible and we hardly notice it. Only significant forces, such as Earth’s gravity acting on people and objects, are enough to be noticed. In stars, gravity is very strong (due to its high mass). When the force of gravity is too great for the atoms to bear, they break the atomic shells and accelerate their nuclei. Hydrogen nuclei (consisting of 1 proton) when collided at high velocity, combine to form heavy hydrogen, and then helium. This reaction releases energy that causes the star to burn brightly. This is a fusion reaction (also known as a nuclear explosion. This reaction is used in the hydrogen bomb (H bomb) – the most destructive destructive weapon that mankind has built). Thanks to the great energy released from nuclear fusion in the star’s core, the gravitational contraction is halted as the released energy balances the gravitational force. The star burns so brightly for several tens, hundreds of millions or billions of years. The lower the mass of the stars, the longer the lifespan. For example, our Sun is a dwarf, medium mass, it can live for about 10 billion years. Meanwhile, stars are much larger, sometimes only living a few hundred or even tens of millions of years because the high mass creates greater pressure towards the center. It causes nuclear fusion to happen faster and the star to deplete energy faster. After burning out all of its hydrogen energy, the star no longer produces energy against centripetal gravity. It will once again shrink. At this time, the helium nuclei combine to form nuclei of heavier elements such as carbon, oxygen and heavier elements up to iron. This process releases an energy that inflates the star’s crust while the star’s core continues to contract. This is the red giant stage. For medium-sized stars (with a mass between 0.5 and 10 times the mass of the Sun), the red giant shell, when inflated sufficiently large, will explode and break up to form a planetary nebula. Meanwhile, high-mass stars have massively inflated stellar shells, becoming red supergiant stars. During this stage, the stellar core continues to contract due to gravity, temperature and pressure both increase many times compared to the previous stage, allowing nuclei of heavier elements to be synthesized (from familiar metals). from copper, silver, and gold to radioactive elements). Up to a certain limit, the energy released from the core creates a large explosion that breaks the outer shell. This is a supervova explosion. After the shell is broken, the star’s core remains for both massive stars as well as light stars. For low- and medium-mass stars like the Sun, the core will stop shrinking, becoming a white dwarf, emitting a very faint light. After billions or tens of billions of years, the generation of radiation ends, stars no longer emit light. It’s called a black dwarf, a dark, dead mass of matter. In fact, the process for a white dwarf to become a black dwarf is so long that so far a black dwarf is only a theoretical prediction. No white dwarf in the universe has been around long enough to become a black dwarf. For massive stars whose core remains after the supervova are at least 1.4 times more massive than the Sun, the mass is so great that they continue to shrink. The nuclei react with each other to form heavy nuclei. The contractions are not over yet, they cause the free electrons to be squeezed tightly against the protons, combining to form neutrons. The star becomes a solid mass of matter, composed entirely of neutrons. Therefore, it has extremely high density and extremely fast rotation speed. This object is called a neutron star. Previously, when this object was first observed, astronomers saw that it emitted a very strong amount of electromagnetic pulses, so they called them pulsars. Even more massive stars with a core mass at least 2 or 3 times that of the Sun, have not stopped after reaching the neutron star stage. They squeeze all matter together to an infinitely large density, concentrated at a location called a singularity. This singularity warps the space around it, a region of space that is bent to an infinite (closed) curvature. The boundary of this space is called the event horizon. Because the space is bent inward, anything that goes in can’t get out, not even light. This entire region of space bounded by the event horizon is called a black hole.