>Earth is unique in the solar system in being the only planet known to support life and to have liquid water at its surface.
>Earth formed,along with the rest of the solar system,around 4.6billion years ago.
>Earth physical environments can be divided into the solid earth, the atmosphere made up of layers of gas,and all the water on the plane, known as the hydrosphere.
>Earth's gravity influenced the formation of the planet, holds its atmosphere in place,and keeps the Moon in orbit around it.
>Eclipse occure when the sun, moon and earth are directly in line.
Saturday, July 3, 2010
One of the earth's most eerie natural displays is the pulsating bands of red, green and yellow light that appear in the skies of the polar regions. This are known as the AURORA BOREALIS (nothern lights) and the aurora australis (southern lights).
These atmospheric fireworks are set off when protons and free electrons released by the sun, and traveling at speeds of around 1,600km/s, collide with atoms or molecules in the earth's atmosphere at altitudes of 80-1,000km. The collisions cause the particles to light up. The aurora occur most frequently in two ring-shaped zones located 23 deg from the magnetic poles.
In these areas, particles approaching the earth are drawn to the poles by the earth's magnetic field.
Posted by switsmile at 2:34 PM