Earth

The third planet from the sun, Earth is the only planet on which life has been found to exist. Scientists believe the earth is about 4.5 billion years old. It consists of tectonic plates and saltwater oceans cover over 70% of the surface. Water that is needed to sustain life is available, unlike the other planets. The interior of the Earth is liquid, with a solid iron inner core and a magnetic outer core.

It takes about 366 days for the Earth to orbit the sun and it spins on its axis once every 24 hours. This is what creates days and years. AS the earth orbits the sun, seasons are created depending on the amount of sunlight and heat it receives from the sun. The moon is a natural satellite, which orbits the earth. The moon also causes tides in the Earth’s oceans, helps to keep the axis tilt stable and helps to slow the speed of the rotation. The earth also has gravity, which keeps objects and people on the ground. This force also affects the rise and fall of the ocean tides.

The earth has a rocky body and is the largest of the terrestrial plants. Although the earth appears round, it actually has an oblong shape with rounded bulges in the center at the equator. The core of the earth is believed to be iron, but it does contain many metals. There is an outer silicate crust, a mantle, a liquid core and a solid inner core. The thickness of the crust varies, ranging from 6 km in the oceans and from 30-60 km in thickness on dry land.

The terrain of the Earth’s surface also varies from one place to another. Some areas a re flat and covered with grasses, while others are rocky and mountainous. Volcanoes are present on the land and under the oceans. Valleys and craters also exist in both places.

The atmosphere surrounding the earth contains oxygen, which allows it to sustain life. The lowest level of this atmosphere is called the troposphere, which receive heat from the sun and causes the air to expand, which in turn creates various weather patterns. Large areas are susceptible to unpredictable weather patterns, such as hurricanes, cyclones and tornadoes. Water vapor rises to the atmosphere, where it is condensed and falls to the earth as precipitation. The water cycle is another essential element for life.