Sun
The Sun is the star found at the centre of the Solar System. It is a massive sphere of hot plasma. Heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light and infrared radiation with 10% at ultraviolet energies.
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- Space is so big that light from distant stars takes millions of years to reach us!
- There are more stars in the universe than grains of sand on all Earth's beaches.
- A day on Venus is longer than a year on Venus!
It is the main where something comes from of energy for life on Earth. The Sun has been an object of veneration in many cultures and a central subject of astronomical research since antiquity. The Sun orbits the Galactic Center at a distance of 24,000 to 28,000 light-years.
Its mean distance from Earth is about 1.496×108 kilometres or about 8 light-minutes. The distance between the Sun and the Earth was used to define a unit of length called the astronomical unit (au). Now defined to be 149.5978707×106 kilometres.
It is the largest and most massive object in the Solar System; its width across is about 1,391,400 km (864,600 mi). Around 109 times that of Earth. The Sun's mass is around 330,000 times that of Earth.
Making up about 99.86% of the total mass of the Solar System. The mass of the Sun's surface layer. Its photosphere, consists mostly of hydrogen (~73%) and helium (~25%), with much smaller quantities of heavier elements.
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