The Inner Planets of Our Solar System

The term inner planets is used to describe the four planets closest to the sun in our solar system. Mercury, Venus, Earth, and Mars, so Mercury is closest to the sun and it takes 88 earth days to orbit the sun.

It has no atmosphere and no moons, but it can be described as having a moon-like surface because it has craters, appears bright and is dense and rocky with a large iron core. Mercury is the smallest planet in our solar system.


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Then there is Venus, which takes 225 earth days to orbit the sun. It has a dense atmosphere, which is made up of carbon dioxide and some sulfur. Venus also has no moons and Venus is similar to Earth in size, gravity, and bulk composition. It’s also very bright. Now, Venus is covered with reflective clouds which are made of sulfuric acid and it exhibits signs of volcanoes. Get this, lighting and thunder have been recorded on Venus’s surface.

Then there is Earth which I’m sure you already know a lot about. Like it takes 365 and a quarter days to orbit the sun and the atmosphere is composed mainly of oxygen and nitrogen and then earth has one moon. About 71 percent of the surface of earth is salt water oceans and therefore the earth is rocky and supports millions of species.

Finally, there’s Mars which takes 687 earth days to orbit the sun. It has a thin atmosphere and two small moons. Then, of course, Mars appears reddish and this is due to iron oxide on the surface. Mars has a rotational period similar to earth. It has seasonal cycles and also an interesting surface feature of Mars include volcanoes, valleys, deserts, and polar ice caps. That’s a look at the four inner planets which can also be referred to as the terrestrial planets.