Inner Planets

Earth
The atmosphere on Earth consists of around 78% nitrogen and 21% oxygen, which humans and other living things need for existence. A layer in Earth’s atmosphere called ozone layer serves as protection from the harmful ultraviolet rays of the sun because it screens ultraviolet radiation. The natural greenhouse effect of the atmosphere prevents the temperature from going down to a chilly 0°C. This means that the heat from the sun can be trapped or retained by Earth’s atmosphere. According to astronomers, Earth’s average temperature is 15°C, which makes Earth a livable planet.

Earth is around 12,756 km in diameter, making the planet slightly bigger than Venus and Mercury. It is about 150 million km away from the sun. You previously learned that it revolves around the sun in a counterclockwise direction. Earth makes one complete revolution in a year or 365.25 days. One complete rotation is about 24 hours or one day. Earth has one moon named Luna that revolves around it, unlike Mercury and Venus with no moons at all.