The Earth is a sphere and it has an atmosphere. The atmosphere of the Earth includes oxygen, nitrogen, carbon dioxide, water vapour and clouds. It is a very big planet.
Earth is the fourth planet in the Solar System and the only huge celestial object known to host and support life, including all forms of animals. About 70% of the earth’s surface is land made up of islands and continents. About 1.6billion people on earth live in places where the planet’s surface is blocked by clouds or from seeing the sun. Astronauts who have been to space have described the earth as “the red planet”. There are about three hundred million stars in the skies and most astronomers think that our planet is one of the few that hold water in its atmosphere – oceans, lakes and rivers.
When astronauts return to earth, they have a great image of the earth as a globe. This happens because the earth obtains almost 100% of its heat from its sun which heats the ocean surface and then evaporates to make clouds. The continents retain some heat and thus maintain weather patterns. Astronomers think that the earth was not created in its current form, but rather that it was created in a cataclysmic impact (a supernovae) on another planet.
Many students in college can recall the first night that they set out to explore space. They used a telescope to see the stars and the moon, but when they got back home they could not see the southern sky. The telescope was too small and did not have sufficient power to correct for the atmosphere. It took about six years for amateur astronomers to use a bigger and more powerful telescope to achieve this result. Today, it is very common to see stars in the night skies above the Indian Ocean in the Southeastern part of Australia and New Zealand.
Students who are planning to travel to outer space have some work to do before they ever leave their dorms or apartments. They should familiarize themselves with the stars, how to measure the phases of the moon, how to calculate and predict solar flares, and learn about the properties of gases that exist in outer space. They also need to know about the magnetism of space, how to observe it, and understand the makeup of space such as plasma and neutral atoms. Astronomy students should be able to determine the size of the gas, ice, and rock that make up the space around them. They will also be able to identify and describe celestial objects like comets, planets, and stars.
As mentioned at the beginning, there is more than one theory about how the earth formed. Geologists believe that the earth was created in a great collision that formed the core of the planet Earth, creating an ocean and a sphere which is still undergoing cooling. Many scientists believe that the earth has undergone a series of different evolutions from a large planet like Earth to the smaller rocky world we know today. It is possible that the moon, one of the known planets, was the original planet. There is also speculation that aliens living on other planets may have contributed to the creation of our world.