**Inner Planets: Chapter Notes - The Earth in the Solar System**

The inner planets, also known as the terrestrial planets, are the four planets closest to the Sun in our solar system. These planets include Mercury, Venus, Earth, and Mars. In this chapter, we will explore the characteristics and features of these inner planets.

**Mercury:**
- Mercury is the closest planet to the Sun, making it the hottest planet in our solar system.
- It has a rocky surface with many craters and cliffs.
- Due to its proximity to the Sun, Mercury has a very thin atmosphere and no moons.
- It takes about 88 Earth days for Mercury to complete one orbit around the Sun.

**Venus:**
- Venus is often referred to as Earth's twin because it is similar in size and composition.
- It has a thick atmosphere composed mainly of carbon dioxide, causing a runaway greenhouse effect and making it the hottest planet in our solar system.
- Venus has no moons and rotates in the opposite direction compared to most other planets.
- It takes about 225 Earth days for Venus to complete one orbit around the Sun.

**Earth:**
- Earth is the third planet from the Sun and the only planet known to support life.
- It has a diverse range of landscapes, including mountains, oceans, and deserts.
- Earth has a moderate climate and a protective atmosphere that allows for the existence of liquid water.
- It takes approximately 365.25 days for Earth to complete one orbit around the Sun, resulting in a leap year every four years.

**Mars:**
- Mars is often called the "Red Planet" due to its reddish appearance caused by iron oxide on its surface.
- It has a thin atmosphere composed mainly of carbon dioxide.
- Mars has polar ice caps and evidence of liquid water in the past, suggesting the possibility of past life.
- It takes about 687 Earth days for Mars to complete one orbit around the Sun.

In conclusion, the inner planets in our solar system are Mercury, Venus, Earth, and Mars. Each planet has its own unique characteristics and features, making them fascinating objects of study. By studying these inner planets, scientists gain insights into the formation and evolution of our solar system.

• There are 4 planets before Asteroids which are called Inner planets.

• There are 4 planets after Asteroids which are called Outer planets.