So today we're going to talk about Sun (it's gonna be a long one, better get your snacks).

The Sun is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma with the internal convective motion that generates a magnetic field through a dynamo process ( A naturally occurring electric generator in the Sun's interior produces electric currents and a magnetic field, following the laws of Ampère, Faraday and Ohm, as well as the laws of fluid dynamics, which together form the laws of magnetohydrodynamics).

galaxy, planet, and space image

It is the most important source of energy for life on Earth. Its diameter is about 1.39 million kilometers (864,000 miles), and its mass is about 330,000 times that of Earth. It accounts for about 99.86% of the total mass of the Solar System. Barely three quarters of the Sun's mass consists of hydrogen (73%) and the rest is mostly helium (25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron.

The Sun is a G-type main-sequence star (often called a yellow dwarf or G dwarf star) based on its spectral class. It formed approximately 4.6 billion years ago from the gravitational collapse of matter within a region of a large molecular cloud.
The Sun currently fuses about 600 million tons of hydrogen into helium every second, converting 4 million tons of matter into energy every second as a result.

earth, planet, and space image
planets, space, and sun image

It is calculated that the Sun will become large enough to engulf the current orbits of Mercury and Venus, and render Earth uninhabitable. After this, it will shed its outer layers and become a dense type of cooling star known as a white dwarf, and no longer produce energy by fusion, but will still glow and give off heat from its previous fusion.

Name and etymology

The English proper name Sun developed from Old English sunne and may be related to south.All Germanic terms for the Sun stem from Proto-Germanic "sunnōn".
The Latin name for the Sun, Sol, is not commonly used in everyday English. Sol is also used by planetary astronomers to refer to the duration of a solar day on another planet, such as Mars. The related word solar is the usual adjectival term used, in terms such as solar day, solar eclipse, and Solar System.

General characteristics

The Sun comprises about 99.86% of the mass of the Solar System. The Sun has an absolute magnitude of +4.83, estimated to be brighter than about 85% of the stars in the Milky Way, most of which are red dwarfs. The Sun is a Population I, or heavy-element-rich, star.
The Sun is by far the brightest object in the Earth's sky, with an apparent magnitude of −26.74. This is about 13 billion times brighter than the next brightest star, Sirius, which has an apparent magnitude of −1.46. The mean distance of the Sun's center to Earth's center is approximately 1 astronomical unit (about 150,000,000 km; 93,000,000 mi). At this average distance, light travels from the Sun's horizon to Earth's horizon in about 8 minutes and 19 seconds, while light from the closest points of the Sun and Earth takes about two seconds less. If the sun exploded we wouldn't know it for 8 mins and 19 secs.

The Sun rotates faster at its equator than at its poles. This differential rotation is caused by convective motion (convection is the heat transfer due to the bulk movement of molecules within fluids such as gases and liquids, including molten rock (rheid), it includes sub-mechanisms of advection, and diffusion) due to heat transport and the Coriolis force due to the Sun's rotation.

planets, fire, and sun image
fire, sun, and planets image

The rotational period is approximately 25.6 days at the equator and 33.5 days at the poles. Viewed from Earth as it orbits the Sun, the apparent rotational period of the Sun at its equator is about 28 days.


The solar constant is the amount of power that the Sun deposits per unit area that is directly exposed to sunlight. The solar constant is equal to approximately 1,368 W/m2 (watts per square meter) at a distance of one astronomical unit from the Sun (that is, on or near Earth).
Sunlight at the top of Earth's atmosphere is composed of about 50% infrared light, 40% visible light, and 10% ultraviolet light.
The Sun's color is white, with a CIE color-space index near (0.3, 0.3), when viewed from space or when the Sun is high in the sky.
When the Sun is low in the sky, atmospheric scattering renders the Sun yellow, red, orange, or magenta.

astronomy, beautiful, and cosmic image

Structure and fusion

The structure of the Sun contains the following layers:

Core – the innermost 20-25% of the Sun's radius, where temperature (energies) and pressure are sufficient for nuclear fusion to occur. Hydrogen fuses into helium. The fusion process releases energy, and the helium gradually accumulates to form an inner core of helium within the core itself.
Radiative zone – Convection cannot occur until much nearer the surface of the Sun. Therefore, between about 20-25% of the radius, and 70% of the radius, there is a "radiative zone" in which energy transfer occurs by means of radiation rather than by convection.
Tachocline – the boundary region between the radiative and convective zones.
Convective zone – Between about 70% of the Sun's radius and a point close to the visible surface, the Sun is cool and diffuses enough for convection to occur, and this becomes the primary means of outward heat transfer.
Photosphere – the deepest part of the Sun which we can directly observe with visible light. Because the Sun is a gaseous object, it does not have a clearly-defined surface; its visible parts are usually divided into a 'photosphere' and 'atmosphere'.
Atmosphere – a gaseous 'halo' surrounding the Sun, comprising the chromosphere, solar transition region, corona and heliosphere. These can be seen when the main part of the Sun is hidden, for example, during a solar eclipse.

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Life phases

The Sun today is halfway through the most stable part of its life. It has not changed dramatically for over four billion years, and will remain fairly stable for more than five billion more. After hydrogen fusion in its core has stopped, the Sun will undergo dramatic changes, both internally and externally.
The Sun formed about 4.6 billion years ago from the collapse of part of a giant molecular cloud that consisted mostly of hydrogen and helium and that probably gave birth to many other stars.
Each second, more than four million tonnes of matter are converted into energy within the Sun's core, producing neutrinos and solar radiation. At this rate, the Sun has so far converted around 100 times the mass of Earth into energy, about 0.03% of the total mass of the Sun. It will spend a total of approximately 10 billion years as a main-sequence star. The Sun is gradually becoming hotter during its time on the main sequence, because the helium atoms in the core occupy less volume than the hydrogen atoms that were fused. Because of that the core is shrinking, allowing the outer layers of the Sun to move closer to the center and experience a stronger gravitational force, according to the inverse-square law.

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Orbit and location

The Sun lies close to the inner rim of the Milky Way's Orion Arm, in the Local Interstellar Cloud or the Gould Belt, at a distance of 7.5–8.5 kpc (25,000–28,000 light-years) from the Galactic Center.
Within 32.6 ly of the Sun there are 315 known stars in 227 systems, as of 2000, including 163 single stars.
The Sun orbits the center of the Milky Way, and it is presently moving in the direction of the constellation of Cygnus.

astronomy, constellations, and stars image
beauty, explore, and gif image
don't look at it for too long, you'll get dizzy

It takes the Solar System about 225–250 million years to complete one orbit through the Milky Way (a galactic year), so it is thought to have completed 20–25 orbits during the lifetime of the Sun.

The Sun has eight known planets. This includes four terrestrial planets (Mercury, Venus, Earth, and Mars), two gas giants (Jupiter and Saturn), and two ice giants (Uranus and Neptune). The Solar System also has at least five dwarf planets, an asteroid belt, numerous comets, and a large number of icy bodies which lie beyond the orbit of Neptune.
A little fact for the end: 109 Earths can fit inside the Sun.

Thanks for reading all of it, it means a lot to me ^‿^