Third Planet: Earth

The third planet from the Sun is Earth. It is the only known planet in the universe to support life. Earth is the largest of the terrestrial planets and the only one with extensive bodies of liquid water. It has a diverse range of environments, including oceans, mountains, forests, and deserts, which support a wide variety of life forms.

Key Facts about Earth

• Diameter: 12,742 kilometers
• Orbital Period: 365.25 days
• Atmosphere: Composed mainly of nitrogen and oxygen
• Surface: 70% covered by water
• Moon: Earth has one natural satellite, the Moon

Composition of Earth

Earth is composed of several layers, including the solid inner core, liquid outer core, mantle, and crust. The crust is divided into several tectonic plates that float on the semi-fluid mantle and interact with each other, leading to geological events such as earthquakes and volcanic eruptions.

Study Guide

Here are some key points to study about the third planet, Earth:

1. Understand the unique characteristics of Earth that make it suitable for life.
2. Learn about the layers of the Earth and their composition.
3. Explore the impact of Earth's tectonic activity on the planet's surface.
4. Study the Earth's atmosphere and the factors that contribute to its composition.
5. Examine the role of Earth's natural satellite, the Moon, in influencing the planet's tides and other phenomena.

By understanding the intricacies of Earth, we gain a deeper appreciation for our home planet and the delicate balance that sustains life.