What are the key characteristics of the Sun?

The Sun is a medium-sized star, primarily composed of hydrogen and helium, and is the central source of energy for our solar system.

The Sun, located at the centre of our solar system, is a medium-sized star that is approximately 4.6 billion years old. It is primarily composed of hydrogen (about 74%) and helium (about 24%), with the remaining 2% consisting of heavier elements such as oxygen, carbon, neon, and iron. The Sun's diameter is about 1.4 million kilometres, which is over 100 times the Earth's diameter.

The Sun's energy is produced through a process called nuclear fusion, where hydrogen atoms combine to form helium, releasing a tremendous amount of energy in the process. This energy is emitted as light and heat, which is what makes life on Earth possible. The Sun's surface, or photosphere, has a temperature of about 5,500 degrees Celsius, while its core can reach temperatures of 15 million degrees Celsius.

The Sun also has a strong magnetic field, which is responsible for solar activity such as sunspots, solar flares, and coronal mass ejections. These phenomena can have significant effects on Earth's magnetosphere and can disrupt satellite communications and power grids.

The Sun is also important for its gravitational pull, which keeps the planets in their orbits around it. Without the Sun's gravity, the planets would simply fly off into space. The Sun's mass is so great that it accounts for about 99.86% of the total mass of the solar system.

In terms of its lifecycle, the Sun is currently in its main sequence stage, which is expected to last for about 10 billion years. After this, it will expand into a red giant and eventually collapse into a white dwarf. This process will take billions of years, so the Sun will continue to be a stable source of energy for a very long time.