vcdiversity.org – The Inner Planets, also known as the Terrestrial Planets, are the four planets in our solar system that are closest to the Sun. They are Mercury, Venus, Earth, and Mars. These planets are called “inner” because they are located before the asteroid belt, which separates them from the outer planets. Here’s a brief overview of each:
- Mercury:
- Mercury is the smallest planet in our solar system and the closest to the Sun.
- It has no natural satellites and a very thin atmosphere, which cannot support life as we know it.
- Mercury’s surface is heavily cratered, similar to Earth’s Moon, and it has extreme temperature variations due to its proximity to the Sun and lack of atmosphere.
- Venus:
- Venus is the second planet from the Sun and is similar in size to Earth, often referred to as Earth’s “sister planet.”
- It has a thick, toxic atmosphere that traps heat due to an extreme greenhouse effect, making it the hottest planet in the solar system.
- Venus rotates very slowly and in the opposite direction to most planets (retrograde rotation), and it has a surface covered in volcanic rock and extensive lava plains.
- Earth:
- Earth is the third planet from the Sun and the only known planet to support life.
- It has a single natural satellite, the Moon, which plays a significant role in its tides and climate.
- Earth’s atmosphere is composed of nitrogen and oxygen, which is vital for life, and it has a large amount of liquid water on its surface, making it unique among the planets.
- Mars:
- Mars is the fourth planet from the Sun and is known as the “Red Planet” due to its reddish appearance, which is caused by iron oxide (rust) on its surface.
- It has a thin atmosphere composed mostly of carbon dioxide, nitrogen, and argon.
- Mars has the largest volcano and the deepest, longest canyon in the solar system, and it also has polar ice caps made of frozen water and carbon dioxide.
All four of these planets are relatively small, rocky, and have solid surfaces, which distinguishes them from the gas giants and ice giants that make up the outer planets. They also have relatively few moons compared to the outer planets, and none have rings like those found around Saturn and Uranus.