Why Can We Live On Earth?

Size And Other Details:

Earth is between Venus and mars in the solar  System and has one satellite, the Moon. The third planet from the sun, it is at a mean Earth's distance of 149. 5 million km. (93 million miles) from the sun. It moves in an elliptic orbit. It is nearest to the Sun on 3 January Plane of the also known as perihelion. The Aphelion or the farthest distance is on 4 July when the earth is 152 million km away from sun. Its equatorial diameter is 12.756 km and polar diameter is 12.712 km.  and the circumference is 40,076 km as compared to the polar circumference of 40,008 km.

The rotation period (duration of day) is 23 hours, 56 minutes and 4.09 seconds. It has an year of 365 days, 5 hours, 48 minutes and 46 seconds. The velocity of Earth's rotation on its axis is 1690 km/h at the equator, some 845 km/h at 60°N and S and zero at the poles. Its average speed round the sun (revolution) is 30 km./18.5 miles a second. The plane of its orbit is inclined to its equatorial plane at an angle of 23.5°, the reason for the changing seasons. 

Earth has a land surface of 150 million sq. km / 57.5 million sq. miles (its greatest height being Mount Everest). Its water surface is 361 million sq. km/139.4 millions sq. miles (its greatest depth being Mariana Trench in the Pacific) The Pole The earth has its axis, the imaginary line on which it rotates. One end of this axis is called the North Pole, and the other the South Pole. The two poles are also called the magnetic poles. In 1960, the north magnetic pole was placed at about latitude 75° North, longitude 101° West and the South magnetic pole at about latitude 67° South, longitude 143° East.

Why Can We Live On Earth?

Earth as a Magnet :

The earth has a strong magnetic field. A bar magnet suspended by a thread eventually comes to rest with one end pointing towards the earth's north magnetic pole, the other towards the south magnetic pole. It behaves as though another bar magnet, or large coil of wire with electricity flowing through it, had been brought near. As the earth spins on its axis, the fluid layer of the outer core allows the mantle and solid crust to rotate relatively faster than the inner core.

As a result, electrons in the core move relative to those in the mantle and crust. It is this electron movement that constitutes a natural generator and creates a magnetic field, similar to that of an

electric coil. Many ore bodies and rocks rich in magnetic minerals have a strong local magnetic field. This is utilized by prospectors using sensitive instruments to detect minerals of economic value.

Another method utilizes natural electrical currents that are set up between the surface and an ore body by percolating ground water. Its interaction with the magnetic field can be measured and

used to locate useful deposits