Sun

solarSolThe Sunsolar magnetic fieldsolar astronomysolar atmospheresolar diametersolar masseslocal starsolar photosphere
The Sun is the star at the center of the Solar System.wikipedia
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Solar System

outer Solar Systeminner Solar SystemSol system
The Sun is the star at the center of the Solar System. The related word solar is the usual adjectival term used for the Sun, in terms such as solar day, solar eclipse, and Solar System.
The Solar System is the gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly.

Earth

terrestrialworldGlobal
It is by far the most important source of energy for life on Earth. It is calculated that the Sun will become sufficiently large to engulf the current orbits of Mercury and Venus, and render Earth uninhabitable.
Earth is the third planet from the Sun and the only astronomical object known to harbor life.

Plasma (physics)

plasmaplasma physicsplasmas
It is a nearly perfect sphere of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process.
The interior of the Sun is an example of fully ionized plasma, along with the solar corona and stars.

Helium

Hesuperfluid heliumhelium II
Roughly three quarters of the Sun's mass consists of hydrogen (~73%); the rest is mostly helium (~25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron.
Its abundance is similar to this figure in the Sun and in Jupiter.

Solar dynamo

dynamodynamo processmagnetic field of the sun
It is a nearly perfect sphere of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process.
The solar dynamo is the physical process that generates the Sun's magnetic field.

Formation and evolution of the Solar System

solar nebulaformation of the Solar Systemoutward
Most of this matter gathered in the center, whereas the rest flattened into an orbiting disk that became the Solar System.
Most of the collapsing mass collected in the center, forming the Sun, while the rest flattened into a protoplanetary disk out of which the planets, moons, asteroids, and other small Solar System bodies formed.

Venus

Morning Starevening starCytherocentric
It is calculated that the Sun will become sufficiently large to engulf the current orbits of Mercury and Venus, and render Earth uninhabitable.
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days.

White dwarf

white dwarfswhite dwarf starcentral star
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 still glow and give off heat from its previous fusion.
A white dwarf is very dense: its mass is comparable to that of the Sun, while its volume is comparable to that of Earth.

Solar core

coreSun's corecore of the Sun
The central mass became so hot and dense that it eventually initiated nuclear fusion in its core.
It is the hottest part of the Sun and of the Solar System.

The Sun in culture

regarded by some culturesSunThe rising sun
The enormous effect of the Sun on Earth has been recognized since prehistoric times, and the Sun has been regarded by some cultures as a deity.
The Sun, as the source of energy and light for life on earth has been a central object in culture and religion since prehistory.

Stellar classification

spectral typeK-typeG-type
The Sun is a G-type main-sequence star (G2V) based on its spectral class.
The full spectral class for the Sun is then G2V, indicating a main-sequence star with a temperature around 5,800 K.

Mars

Martianplanet MarsRed Planet
Sol is also used by planetary astronomers to refer to the duration of a solar day on another planet, such as Mars.
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System after Mercury.

Solar mass

mass of the SunSun's masssolar masses
Its diameter is about 1.39 million kilometers (864,000 miles), or 109 times that of Earth, and its mass is about 330,000 times that of Earth.
It is equal to the mass of the Sun (denoted by the solar symbol ⊙︎).

Solar eclipse

solar eclipsessolareclipse
The related word solar is the usual adjectival term used for the Sun, in terms such as solar day, solar eclipse, and Solar System.
A solar eclipse occurs when an observer (on Earth) passes through the shadow cast by the Moon which fully or partially blocks ("occults") the Sun.

Carbon

Ccarbonaceouscarbon atom
Roughly three quarters of the Sun's mass consists of hydrogen (~73%); the rest is mostly helium (~25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron.
Carbon compounds form the basis of all known life on Earth, and the carbon–nitrogen cycle provides some of the energy produced by the Sun and other stars.

Sunday

Suday of the sunfirst day of each week
The English weekday name Sunday stems from Old English (Sunnandæg; "Sun's day", from before 700) and is ultimately a result of a Germanic interpretation of Latin dies solis, itself a translation of the Greek ἡμέρα ἡλίου (hēméra hēlíou).
The name "Sunday", the day of the Sun, is derived from Hellenistic astrology, where the seven planets, known in English as Saturn, Jupiter, Mars, the Sun, Venus, Mercury and the Moon, each had an hour of the day assigned to them, and the planet which was regent during the first hour of any day of the week gave its name to that day.

Sunlight

sunshinesolar radiationnatural light
The energy of this sunlight supports almost all life on Earth by photosynthesis, and drives Earth's climate and weather.
Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light.

Astronomical unit

AUastronomical unitsAUs
The solar constant is equal to approximately 1368 W/m2 (watts per square meter) at a distance of one astronomical unit (AU) from the Sun (that is, on or near Earth).
The astronomical unit (symbol: au, ua, or AU) is a unit of length, roughly the distance from Earth to the Sun.

G-type main-sequence star

yellow dwarfGG-type
The Sun is a G-type main-sequence star (G2V) based on its spectral class.
The Sun, the star to which the Earth is gravitationally bound in the Solar System and the object with the largest apparent magnitude, is an example of a G-type main-sequence star (G2V type).

Red dwarf

redred dwarf starsred dwarfs
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.
Red dwarfs are by far the most common type of star in the Milky Way, at least in the neighborhood of the Sun, but because of their low luminosity, individual red dwarfs cannot be easily observed.

Solar constant

energy from the starheatintensity at Earth orbit
The solar constant is the amount of power that the Sun deposits per unit area that is directly exposed to sunlight.
The solar constant (G SC ) is a flux density measuring mean solar electromagnetic radiation (solar irradiance) per unit area.

Absolute magnitude

Hbolometric magnitudeabsolute magnitude (H)
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 has absolute magnitude M V =+4.83.

Red giant

red giant starred giantsred giant stars
In about 5 billion years, when hydrogen fusion in its core has diminished to the point at which the Sun is no longer in hydrostatic equilibrium, its core will undergo a marked increase in density and temperature while its outer layers expand to eventually become a red giant.
They have radii tens to hundreds of times larger than that of the Sun.

Star formation

star-forming regionnew starsstar-forming
It is thought that almost all stars form by this process.
The nearest nebula to the Sun where massive stars are being formed is the Orion nebula, 1300 ly away.

Solar rotation

rotation of the Sundifferential rotation24.47 days
This differential rotation is caused by convective motion due to heat transport and the Coriolis force due to the Sun's rotation.
Solar rotation varies with latitude because the Sun is composed of a gaseous plasma.