Earth

Earth is the third nearest planet to the Sun. It has an equatorial diameter of 12,756 km. and a polar diameter of 12,714 km. The earth is at a distance of 149,597,900 km. from the Sun and orbits round the Sun at a speed of 107,220 km per hour, making one revolution in 365 days, 5 hours, 48 minutes and 45.51 seconds. It completes one rotation at its axis every 23 hours, 56 minutes and 4.091 seconds.

Earth is the only planet in the solar system known to harbor life. Our planet's rapid spin and molten nickel-iron core give rise to an extensive magnetic field, which, along with the atmosphere, shields us from nearly all of the harmful radiation coming from the Sun and other stars. Earth's atmosphere protects us from meteors, most of which burn up before they can strike the surface.

Earth is slightly t pear shaped with a 18 meter rise in north pole and 26 meter depression on the south pole.

There is an intense radiation zone, now called the Van Allen radiation belts round the Earth. This layer is formed from rapidly moving charged particles that are trapped by the Earth's magnetic field in a doughnut-shaped region surrounding the equator. Findings from satellites show that our planet's magnetic field is distorted into a tear-drop shape by the solar wind. We also now know that our wispy upper atmosphere, once believed calm and uneventful, seethes with activity -- swelling by day and contracting by night. Affected by changes in solar activity, the upper atmosphere contributes to weather and climate on Earth.

Besides affecting Earth's weather, solar activity gives rise to a dramatic visual phenomenon in our atmosphere. When charged particles from the solar wind become trapped in Earth's magnetic field, they collide with air molecules above our planet's magnetic poles. These air molecules then begin to glow and are known as the auroras or the northern and southern lights.

Views of Earth

Cosmos...