The Sun is the star at the center of the Solar System.

It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields.

The Sun is currently traveling through the Local Interstellar Cloud in the Local Bubble zone, within the inner rim of the Orion Arm of the Milky Way galaxy.

The English proper noun Sun developed from Old English sunne (in around 725, attested in Beowulf), and may be related to south.

The English weekday name Sunday is attested in 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 from Greek.

Sunlight is Earth's primary source of energy. The only other source of energy the Earth has are the fissionable materials generated by the cataclysmic death of another star. These fissionable materials trapped in the Earth's crust is what gives rise to geothermal energy, which drives the volcanism on Earth while also making it possible for mankind to fuel nuclear reactors.

The Egyptians portrayed Ra (the sun) as being carried across the sky in a solar barque, accompanied by lesser gods, and to the Greeks, he was Helios, carried by a chariot drawn by fiery horses. From the reign of Elagabalus in the late Roman Empire the Sun's birthday was a holiday celebrated as Sol Invictus (literally “unconquered sun”) soon after the winter solstice which may have been an antecedent to Christmas. Regarding the fixed stars, the Sun appears from Earth to revolve once a year along the ecliptic through the zodiac, and so Greek astronomers considered it to be one of the seven planets (Greek planetes, “wanderer”), after which the seven days of the week are named in some languages.