Sun SVG is one of the stars of our galaxy (the Milky Way) and the only star of the solar system. Other objects of this system are circulating around the Sun: planets and their satellites, dwarf planets and their satellites, asteroids, meteoroids, comets and cosmic dust.
According to the spectral classification, the Sun belongs to the G2V type (yellow dwarf). The average density of the Sun is 1.4 g/cm³ (1.4 times higher than that of water). The effective temperature of the Sun’s surface is 5780 Kelvin. Therefore the Sun shines almost white light, but direct light of the Sun at a surface of our planet gets some yellow shade because of stronger scattering and absorption of a short-wave part of a spectrum by atmosphere of the Earth (at the clear sky, together with the blue scattered light from the sky, sunlight again gives white illumination).
Solar radiation supports life on Earth (light is necessary for the initial stages of photosynthesis), determines the climate.
Sun SVG consists of hydrogen (≈73% of mass and ≈92% of volume), helium (≈25% of mass and ≈7% of volume) and other elements with lower concentrations: iron, nickel, oxygen, nitrogen, silicon, sulfur, magnesium, carbon, neon, calcium and chromium. There are 98,000 helium atoms, 851 oxygen atoms, 398 carbon atoms, 123 neon atoms, 100 nitrogen atoms, 47 iron atoms, 38 magnesium atoms, 35 silicon atoms, 16 sulphur atoms, 4 argon atoms, 3 aluminium atoms, 2 nickel, sodium and calcium atoms each, and a small number of other elements per 1 million hydrogen atoms. The mass of the Sun is 99.866% of the total mass of the entire solar system.
The solar spectrum contains lines of ionized and neutral metals, as well as hydrogen and helium. In our Galaxy (the Milky Way) there are from 100 to 400 billion stars. At the same time, 85% of the stars in our galaxy are less bright than the Sun (mostly red dwarfs). Like all stars of the main sequence, the Sun produces energy by thermonuclear synthesis. In the case of the Sun, the vast majority of the energy is produced by the synthesis of helium from hydrogen.
Sun SVG is the nearest star to the Earth. The average distance of the Sun from the Earth – 149.6 million km – is approximately equal to the astronomical unit, and the visible angular diameter when observing from the Earth, as well as the Moon – a little more than half a degree (31-32 minutes). The sun is about 26,000 light-years away from the center of the Milky Way and revolves around it, making one revolution in 225-250 million years. The orbital speed of the Sun is 217 km/s – thus, it passes one light year in 1400 Earth years, and one astronomical unit – in 8 earth days.
At present, the Sun is located in the inner edge of the Orion arm of our Galaxy, between the Perseus arm and the Sagittarius arm, in the so-called Local Interstellar Cloud, an area of increased density, located, in turn, in the lower density of the Local Bubble, a zone of scattered high-temperature interstellar gas. Of the stars belonging to the 50 closest stellar systems within 17 light-years known today, the Sun is the fourth brightest star (its absolute star value is +4.83m).
Sun SVG General information
The sun belongs to the first type of star population. One of the most common theories of the solar system is that its formation was caused by the explosions of one or more supernovae. This assumption is based, in particular, on the fact that the substance of the Solar System contains an abnormally large proportion of gold and uranium, which could be the result of endothermic reactions caused by this explosion, or of nuclear transformation of elements by absorbing neutrons by the substance of a massive second-generation star.
Sun radiation is the main source of energy on Earth. Its power is characterized by a solar constant – the power of radiation passing through the site of a unit area perpendicular to the sun’s rays and located at a distance of one astronomical unit from the Sun (i.e. in the orbit of the Earth) outside the Earth’s atmosphere. This constant is approximately 1.37 kW/m².
Passing through the Earth’s atmosphere, solar radiation loses approximately 370 W/m² of energy and only reaches the Earth’s surface of 1000 W/m² (in clear weather and when the Sun is at its zenith). This energy can be used in various natural and artificial processes. For example, plants use this energy to synthesize organic compounds and release oxygen. Direct solar heating or photovoltaic energy conversion can be used to produce electricity (solar power plants) or perform other useful work. Through photosynthesis, energy stored in oil and other fossil fuels was also obtained in the distant past.
Ultraviolet radiation of the Sun has antiseptic properties, allowing it to be used for disinfection of water and various objects. It also causes tanning and other biological effects, such as stimulating the production of vitamin D in the body. Exposure to the ultraviolet part of the solar spectrum is strongly attenuated by the ozone layer in the Earth’s atmosphere, so the intensity of ultraviolet radiation on the Earth’s surface varies greatly with latitude. The angle at which the sun is above the horizon at noon affects many types of biological adaptation – for example, it affects the color of human skin in different regions of the world.
The path of the Sun observed from the Earth through the celestial sphere changes over the course of the year. The path described during the year by the point that the Sun occupies in the sky at a given time is called an analemma and takes the form of a number 8, stretched along the north-south axis. The most noticeable variation in the visible position of the Sun in the sky is its oscillation along the north-south direction with an amplitude of 47° (caused by the inclination of the ecliptic plane to the celestial equator plane equal to 23.5°). There is also another component of this variation, directed along the east-west axis and caused by an increase in the speed of the Earth’s orbital motion as it approaches the perihelion and a decrease in its speed as it approaches the swindle. The first of these movements (north-south) causes a change in seasons.
The Earth passes through a point of swindle in the beginning of July and moves away from the Sun on distance of 152 million km, and through a point of perihelion – in the beginning of January and comes nearer to the Sun on distance of 147 million km. The visible diameter of the Sun between these two dates varies by 3%. Since the difference in distance is about 5 million km, in swindle the Earth gets about 7% less heat. Winters in the northern hemisphere are thus slightly warmer than in the southern hemisphere, and summers are slightly cooler.
The sun is a magnetoactive star. It has a strong magnetic field, the intensity of which changes over time and which changes direction approximately every 11 years, during the solar maximum. Variations in the magnetic field of the Sun cause a variety of effects, a combination of which is called solar activity and includes phenomena such as sunspots, solar flares, solar wind variations, etc., and on Earth causes polar lights in high and middle latitudes and geomagnetic storms, which adversely affect the operation of communication facilities, means of transmission of electricity, as well as negatively affects living organisms (cause headaches and ill health in people sensitive to magnetic storms). It is assumed that solar activity has played a major role in the formation and development of the solar system. It also affects the structure of the Earth’s atmosphere.