- Earth is estimated to be 4.54 billion years old.
- The earth's equatorial perimeter is 40,067 km and the equatorial diameter is 12,757 km.
- Earth's polar perimeter is 40,075 km and the polar diameter is 12,714 km.
- The total surface area of the earth is 510,100,500 sq. km.
- 71 % of the total surface area of the earth is water (hydrosphere) and 29% is land area (lithosphere).
- Percentage of fresh water on the earth is 3% while 97% of the water AIs salt water(in sea).
- The earth is made up of three layers - Crust, mental and core (central part).
- The rotation period of the earth is 23 hours 56 minutes 4.091 seconds.
- The speed of rotation on the equator is 1674 km per hour.
- For calculating the constellation day, the sun is considered as rotating around the galaxy. This day is of 23 hours 56 minutes.
- For calculating the solar day it is considered that sun is motionless and by calculating movement of the earth around it. Star day is smaller than solar day.
- Escape velocity on earth is 11.186 km/second.
- The highest point on the earth is Mount Everest at an elevation of 8,848 meters.
- The deepest trough on the earth is the Mariana Trench in a valley in its floor known as Challenger Deep which is located in the Pacific Ocean and its depth is 10,994 meters.
Today the temperature of earth is increasing due to "Green House" as a result of "global warning".
Green House Effect :-The greenhouse effect is a natural process that warms the Earth’s surface. When the Sun’s energy reaches the Earth’s atmosphere, some of it is reflected back to space and the rest is absorbed and re-radiated by greenhouse gases.
But due to humans activities it increases green house gases like :- water vapour, carbon dioxide, methane, nitrous oxide, ozone and some artificial chemicals such as chlorofluorocarbons (CFCs). And increases of green house gases had made a layer of this gases that blocks the radiation of sun that has to go back into the space. But due to layer of green house gases it dose not go to space and the temperature of earth is increasing.
As a result it makes "global warming "
When the sun radiation that has to go to space is blocked by layer of green house gases then the radiation is back to the earth surface and start heating the earth.
As result the glacier are started melting and the level of hydrosphere(sea & ocean) is increasing. The island country like :- Sri Lanka, Australia, etc. getting in the water of sea.
- Increase in Earth temperature.
- climate change.
- Increase in environmental temperature.
- harmful effects on humans body.
