The Sun's Interior
The interior of the sun consists of 3 layers. The core is the innermost layer of the sun. This is where the sun's energy is produced. Temperature and pressure are so high that nuclear fusion occurs. The core is about 400,000km in diameter. The radiation zone is the middle layer. Energy from the core moves outward through the radiation zone. This is a region of tightly packed gas where energy is transferred through electromagnetic radiation. This layer is very dense, taking up 70% of the Sun's radius. The convection zone is the outermost layer. Hot gases rise from the convection zone and cool as they rise. The cooler gases sink, forming loops of gas carrying energy toward the sun's surface.
The Sun's Atmosphere
The Sun's atmosphere includes three layers. The innermost layer is the photosphere. This layer is dense enough for the gases to be visible. Here, the temperature is relatively cool. The photosphere consists of many granules, cells of gas 1,000km in diameter. Each lives for 8-9 minutes. The middle layer is the chromosphere. During a solar eclipse, the moon blocks out the photosphere, allowing you to see the faint chromosphere. This layer creates a red glow. The chromosphere consists of spicules, spikes of gas that rise through it. The outermost layer is the corona. During a solar eclipse, the corona will create a white halo around the sun, extending into space. It ends in streams of electrically charged particles, the solar wind.
The Sun produces energy by nuclear fusion, when two atomic nuclei combine to form larger particles, releasing energy. Hydrogen atoms join to form helium in the sun. Nuclear fusion occurs in the core, where the temperature reaches about 15 million degrees Celsius. The leftover mass created by nuclear fusion is changed into heat and light. Gravity balances the force to prevent the sun from exploding. This way the weight of matter pressing inward and outward is balanced, keeping the sun stable.
Features of the Sun
Sunspots are areas of gas on the sun's surface that are cooler than the gases around it. They do not give as much light, making sunspots look darker than the surface. Sunspots move across the sun's surface with its rotation. Prominences are huge red loops of gas that link different parts of sunspot regions. Solar flares are loops in sunspot regions that connect. Large amounts of magnetic energy is converted into thermal energy, heating gas on the sun. This causes the gas to erupt into space. Solar wind is found in the corona. Solar flares can increase the solar wind. This results in auroras at the North and South Pole of the Earth. This can also disrupt Earth's magnetic field.