The
Sun
The Sun is a star, a huge ball of burning gas that sends heat far
into the solar system. It plays a very important part in our
everyday lives. Its heat supports life on Earth, powers
photosynthesis in plants, and is the source of all food and
fossil fuels. It causes seasons, climate, currents in oceans,
circulation in air, and the weather in our atmosphere (3). The
Sun has been around for about 4.6 billion years and is expected
to keep burning bright for another 5 billion years (2).
The Sun is considered to be a medium sized star, has a diameter
of about 1.35 million km (100x the diameter of Earth) (1), and is
about 333,400x more massive than the Earth (3). It contains about
99.86% of all the matter in the entire solar system (3). It is
composed of roughly 75% hydrogen, 25% helium, and less than 1%
oxygen and other elements (2).