Earth, one of the four planets in the solar system, is an extremely important planet in our search for habitable environments for ourselves and for other life forms. It is a highly populated planet in a solar system that also consists of several moons. In fact, it is one of the solar system’s most crowded planets in relation to its size, with only Venus (the second most populated planet) having more surface area than Earth.

Earth is a hothouse for life, being the only inner planet that has differentiated weather from atmospheric pressure. This makes it a prime location for the development of advanced life forms such as bacteria and algae, both requiring suitable temperatures, a solid surface and water to breathe. Earth also possesses a large fraction of iron in its surface area, which is essential for the production of metalloprotein molecules. Earth is also the only celestial body known to harbour and support complex life, with the entire planet being capable of supporting life.

The fraction of the planet’s surface area that is covered with oceans contains about two-thirds of Earth’s total surface area. About 29.2 percent of Earth’s surface area is land, consisting of islands and continents. Water accounts for about two-thirds of the planet’s atmosphere, and about two-thirds of the planet’s total surface area. Only a small fraction of the Earth’s total volume of all the earth’s air is made up of oxygen. The Earth’s atmosphere is composed of water vapour, which constitute about two-thirds of the atmosphere, and carbon dioxide, which constitute about a quarter of the atmosphere. Other elements include nitrogen and oxygen.

The Earth is very similar to a “gas planet” in that it has a greenhouse effect that causes surface temperatures to warm unevenly through evaporation. This uneven heating effect is essential in the evolution of life on Earth. This process generates a great deal of heat in the atmosphere, and this contributes to the planet’s climate. Because the solar system consists of many small bodies, it is likely that the planets in our solar system have also had climates based on convective currents.

The Earth’s orbit is tilted relative to the solar system, and it takes about 4.5 days for the earth to complete one orbit around the sun. It takes about 26.6 Earth days to rotate once, and the planet’s axis of rotation is tilted within about forty-five degrees from its axis of revolution around the solar system. This mean orbital period gives us an average of nearly four and a half Earth days in a year. Thus, on a yearly average, the earth completes an orbit for a full day about once every approximately five years. Of course, variations in seasons and months, and the planet’s position in relation to the sun can affect the time between each orbit.

In addition to the earth’s orbit and tilt, the earth’s composition can affect the amount of gases produced and transferred to and from it. The composition of carbon dioxide, nitrogen, and oxygen in the atmosphere is very different than the composition of water, oil, and gas, which means that those gases do not mix as readily with the atmosphere, which results in a slower transfer. Thus, while clouds may form, they tend to stay in confined areas where the concentration of greenhouse gases is low. As clouds grow, however, clouds can move into locations with higher concentrations of greenhouse gases, creating a cycle that can cause the atmospheric concentration to rise to unacceptable levels.