Earth

Earth is the third planet from the sun and the only known planet in the universe that supports life. It is made up of land, water, air, and living things. Earth is shaped like a slightly flattened sphere called an oblate spheroid. It spins around its own axis once every 24 hours, creating day and night, and travels around the Sun once every 365 days, making one year.

Earth has four main layers: the crust, mantle, outer core, and inner core. The crust is the thin outer layer where we live, made up of rocks, soil, and oceans. Beneath it is the mantle, a thick layer of hot, flowing rock. The core, found deep inside, is mostly made of iron and nickel. The outer core is liquid, and the inner core is solid because of the high pressure. These layers work together to create the planet’s shape, mountains, and even volcanic activity.

Most of Earth’s surface—about 71%—is covered by water, mainly in oceans, seas, and lakes. The remaining 29% is land, which includes continents and islands. Water is essential for all living things. It moves around the planet in a process called the water cycle, where it evaporates, forms clouds, and falls back as rain or snow. This process keeps rivers, plants, and animals alive.

Earth’s atmosphere is a layer of gases surrounding the planet. It contains oxygen, which people and animals need to breathe, and carbon dioxide, which plants use to make food. The atmosphere also protects life by blocking harmful rays from the Sun and keeping the planet warm enough to live on through the greenhouse effect.

The planet’s surface is constantly changing because of plate tectonics. The Earth's crust is divided into large plates that slowly move, creating mountains, earthquakes, and volcanoes. Over millions of years, this movement has shaped continents and oceans. Earth also has a natural satellite, the moon, which affects tides and stabilizes the planet’s rotation.

Earth is home to millions of species of living things, from tiny bacteria to large animals and humans. It provides air, food, and resources needed for survival. Taking care of our planet is important because pollution and climate change can harm its delicate balance. By protecting nature, using energy wisely, and reducing waste, people can help keep Earth healthy for future generations.