The star is a cluster of glowing gases, usually hydrogen and helium, which emits light and heat due to the nuclear and thermonuclear reactions taking place in it.
The closest star to us is the Sun, the star closest to our solar system is 4.5 light years away (the distance that light passes for 1 year) from Earth.
By terrestrial standards this is a huge figure.
Studying stars, mankind was engaged withAncient times. The results of the research were used for navigating seafarers and determining the time. Until recently, the main tool of astronomers were the simplest telescopes, which allowed you to monitor the stars. In our days, in the study of stars, in addition to conventional optical telescopes, radio telescopes are used, which record not visible light of the star, but electromagnetic radiation emanating from it. The radio telescope allows you to explore stars that are much more distant than the reach of optical telescopes.
Separately it is worth noting the orbiting telescope "Hubble", which allowed to conduct observations, which did not interfere with the Earth's atmosphere and adverse weather conditions.
In addition to optical and radio telescopes, astronomersThey use special photographic equipment for viewing stars, which photographs large areas of the starry sky with high exposures. A large exposure allows radiation from weak stars to accumulate, which subsequently makes them visible in the images. Photos are then used to search for new stars that can not be detected in other ways, because their radiation is too weak.
Another very important way to study starsIs a spectral analysis. With the help of spectral analysis, scientists can determine the temperature on the surface of the star, the chemical composition of the substance of the star and the nature of its displacements in the universe. All stars are divided into spectral classes, stars of the same class have the same color. This color can range from red to blue. The color of the spectrum depends on the temperature of the star: the hottest stars are blue, the temperature of their surface starts from 25000 degrees, the red stars are the coldest, their temperature usually does not exceed 1600 degrees. Determine the presence of a chemical element in the star can be compared with the spectrum of the element with parts of the spectrum of the star. Helium and hydrogen, the elements of which stars consist, are also found on Earth.