About three quarters of the sun is hydrogen, which is constantly fusing together and creating helium by a process called nuclear fusion. This means the particles have an increased or reduced number of electrons. These gases are actually in the form of plasma. Plasma is a state of matter similar to gas, but with most of the particles ionized. The sun’s mass is more than 333,000 times that of Earth, and contains about 99.8 percent of all of the mass in the entire solar system! Composition The sun is made up of a blazing combination of gases. The sun not only has a much larger radius than Earth-it is also much more massive. That distance is about 109 times the size of Earth’s radius. The radius of the sun, or the distance from the very center to the outer limits, is about 700,000 kilometers (432,000 miles). It takes light on the sun about eight minutes and 19 seconds to reach Earth. An AU can be measured at light speed, or the time it takes for a photon of light to travel from the sun to Earth. This distance, called an astronomical unit (AU), is a standard measure of distance for astronomers and astrophysicists. The sun is about 150 million kilometers (93 million miles) from Earth. Other parts of the molecular cloud cooled into a disc around the brand-new sun and became planets, asteroids, comets, and other bodies in our solar system. Eventually, the gases heated up enough to begin nuclear fusion, and became the sun in our solar system. Much of the hydrogen and helium remained in the center of this hot, rotating mass.
As one of these regions collapsed, it also began to rotate and heat up from increasing pressure. The molecular cloud began to compress, and some regions of gas collapsed under their own gravitational pull. A nearby supernova emitted a shockwave, which came in contact with the molecular cloud and energized it. About 4.5 billion years ago, the sun began to take shape from a molecular cloud that was mainly composed of hydrogen and helium. Without the sun’s heat and light, life on Earth would not exist. The sun has extremely important influences on our planet: It drives weather, ocean currents, seasons, and climate, and makes plant life possible through photosynthesis. The sun is an ordinary star, one of about 100 billion in our galaxy, the Milky Way.
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