Sun


SUN


•         The Sun is a star.

•         Our Sun is just like the other stars, we see in the night sky.

•         It is also the only star that we see during the daytime.

•         It is the closest star to the Earth, about 1.5 million kilometres away.

•         It is a huge ball of hot, burning gases.

•         The temperature at the centre of the sun is about 15 billion degree Centigrade (°C), and on the surface, it is about 6000 °C.

•         The sun has a thin layer of atmosphere called the corona.

•         It is this corona that we sometimes see during a solar eclipse.

Figure 7: The Sun

•         The spherical sun has a diameter of 13,92,000 km.

•         The sun is so big that a million Earths could fit into it.

•         It measures more than a million kilometres across.

•         But it is still considered small because stars are usually much larger.

•         In fact, the sun is called a dwarf star.

•         The sun is made up of about 75% hydrogen and 25% helium.

•         Helium is at the centre of the sun.

•         The hydrogen around it is constantly changing into helium and this releases heat and light energy.

•         This change takes place slowly over time as the hydrogen changes to helium in its core (centre).

•         It is this light and heat that we receive on Earth.

•         Solar energy is the most important source of energy for us.

•         It is almost inexhaustible.

•         While sunlight is very important and useful, there is some part of it, called ultraviolet rays, that is harmful to us.

•         The Earth's atmosphere has a layer called the ozone layer that protects us from the harmful effects of these rays.