List the conditions favourable to life on earth.

The conditions favourable to life on earth are:

1. The position of earth in solar system is such that it is neither too far nor too near to the sun. Hence, it receives just the right amount of heat necessary for life.
2. The atmosphere of other planets is either too thin or too dense, full of poisonous gases, making it impossible for life to exist. On the other hand, earth's atmosphere extends up to 1600 km and contains adequate amount of nitrogen (78%), oxygen (21%) and other gases like helium, carbon dioxide and water vapour.
3. It acts as a blanket, protecting us from harmful ultraviolet rays of the sun, and retains the heat radiated from the earth's surface.
4. Earth's water cycle is the most unique feature. Water is essential for the existence of life.