The Sun, also known as Sol, is a star at the center of the solar system. It is a white star that gives off different types of energy such as infrared energy (heat), ultraviolet light, radio waves and light. It gives off the light and heat that make life on Earth possible. Without it, Earth would be a frozen, lifeless place. It is a huge ball of hot gases, mostly hydrogen and helium.
The Sun is nearly a perfect sphere and has a diameter of about 1.39 million kilometers (or 864,000 miles), which is about 109 times wider than Earth. Its mass is 333,000 times heavier than Earth, and it makes up over 99.8% of all the mass in the Solar System. That is why its gravity controls the movement of all the planets, moons, asteroids, and comets. The Sun’s energy comes from nuclear reactions deep inside it, where hydrogen is turned into helium. This process releases a lot of energy, which travels as light and heat across space to reach Earth. It takes about 8 minutes for sunlight to travel the 150 million kilometers (93 million miles) from the Sun to Earth. This distance is called 1 Astronomical Unit (AU). The Sun is also part of the Milky Way galaxy, slowly orbiting around the galaxy’s center at a distance of about 24,000 to 28,000 light-years. Its outer layer, called the photosphere, is mostly hydrogen (~73%) and helium (~25%), but also contains tiny amounts of other elements like oxygen, carbon, neon, and iron.
The Sun is a type of star called a G-type main-sequence star, sometimes nicknamed a yellow dwarf, even though its light is actually white, not yellow. It looks yellow because of the atmosphere. Sunlight is made up of all the colors, red, orange, yellow, green, blue, indigo, and violet. When sunlight passes through Earth’s atmosphere, the shorter wavelengths, like blue and violet, get scattered in all directions. That is also why the sky looks blue. The longer wavelengths, like yellow and red, do not scatter as much, so they reach our eyes more directly. That is why the Sun looks yellow when it is seen from the ground. But if the Sun is seen from space, where there is no atmosphere, it would look white, which is its real color.
The Sun was born about 4.6 billion years ago. It formed when a huge cloud of gas and dust in space began to collapse under its own gravity. Most of the material got pulled into the center, which became the Sun. The leftover material flattened into a spinning disk and formed the planets, moons, asteroids, and comets, creating the Solar System. As the Sun's core got hot and dense, it started a process called nuclear fusion. This is when hydrogen atoms combine to make helium, releasing an enormous amount of energy. Every second, the Sun turns about 600 billion kilograms of hydrogen into helium and converts 4 billion kilograms of matter into energy. This energy is what gives us sunlight and heat, keeping our planet warm and life-friendly.
The Sun gives off a stream of particles, which reaches Earth as "solar wind". The source of all this energy is nuclear fusion. Nuclear fusion is the reaction in the star which turns hydrogen into helium and makes huge amounts of energy. It is a nearly perfect ball of hot plasma. The Sun looks yellow to people on Earth, but it is really white. The Sun is a star like many others in our Milky Way galaxy. The Sun is a type of star called a G-type main-sequence star based on its spectral class.