Earth

Our Beautiful Earth

Earth is our home! It is the third planet from the Sun and the only place we know that can harbor life. Earth is special because it is an ocean world. Most of its surface is covered by liquid water, which makes up about 70.8% of Earth's crust. The rest is land where we live and grow food.

Earth has a layer of air called an atmosphere. This air is made mostly of nitrogen and oxygen. It helps keep Earth at the right temperature for water to stay liquid. Earth is rounded like a ball. If you could travel around it, it would be about 40,000 kilometers!

Earth moves in two ways. First, it orbits it the Sun. One trip around the Sun takes about 365.25 days, which we call a year. Second, Earth spins around its own center. This spin takes a little less than a day, which we call a day. Because Earth is tilted, we have different seasons like summer, winter, spring, and fall.

Earth has a friend called the Moon. The Moon helps control our tides, which are the rising and falling of the ocean water. Life on Earth began a very long time ago in the water. We all depend on Earth's biosphere and its natural gifts to live.

The word Earth comes from old languages. In Old English, it was written as eorðe. Some early stories thought of Earth like a mother, even a goddess. Later, people began using a capital letter when talking about our planet.

Earth formed about 4.5 billion years ago from a cloud of dust and gas. It grew by pulling in more material. Early Earth had no air or water, but volcanic activity helped create both. Over time, Earth cooled and hardened. The movement of its plates made the continents we see today.

Earth is round like an egg because of how it spins. It is the fifth largest planet in our Solar System and the largest of the rocky planets. Inside Earth, there are several layers. The outer layer is a solid crust. Below the crust is a thick, soft layer called the mantle. Deep inside is a hot, liquid outer core and a solid inner core.

Earth's surface is where we live. Most of it is covered by water—about 70.8%. This makes Earth a water world. The water is split into five big parts: the Pacific, Atlantic, Indian, Southern, and Arctic Oceans. The land makes up about 29.2% of Earth. This land has places like Antarctica, Africa, Europe, Asia, Australia, and many islands.

Earth's land and ocean floors form the top layer of Earth's crust. The land has many different shapes, such as mountains, deserts, and flat areas. The ocean floor also has different shapes, including deep valleys and underwater mountains.

Earth's outer layer, the lithosphere, is split into pieces called tectonic plates. These plates move around slowly. When they push together, pull apart, or slide past each other, they can cause earthquakes and volcanic activity.

Earth's atmosphere has a pressure of about 101.325 kPa at sea level. It is mostly made of nitrogen (78.084%) and oxygen (20.946%), with small amounts of other gases. Water vapor makes up a tiny part of the air. The atmosphere has several layers. The troposphere is the bottom layer, where most weather happens. Above it are the stratosphere, mesosphere, and thermosphere.

Earth spins around once every 24 hours. We call this a day. Earth also moves around the Sun. This takes about 365 days and we call this a year. Earth is tilted on its axis. Because of this tilt, different parts of Earth get more sunlight at different times. This causes seasons like summer and winter.

Earth's gravity is what keeps everything on the ground and gives objects their weight. Near the surface, things fall at about 9.8 meters per second squared. Earth’s gravity can reach out about 1.5 million kilometers.

The Moon is Earth’s natural satellite and is quite large compared to the planet it orbits. It is about a quarter of Earth’s diameter. The Moon and Earth orbit a common point every 27.32 days. Because of the Moon’s distance from Earth, it appears almost the same size as the Sun in the sky, which allows for solar eclipses. The Moon’s gravity causes tides in Earth’s oceans.

Earth is the only place we know where life can exist. Life began in Earth's water about 4 billion years ago. Earth gives us liquid water, which helps living things grow and stay alive. Plants and animals take nutrients from water, soil, and air, and these nutrients move between different kinds of living things.

Humans came from earlier primates in Africa about 300,000 years ago. They have since spread all over Earth. With farming, they began to live on land. By the 1900s, humans had reached Antarctica, the last continent. The number of humans has grown fast since the 1800s. It reached eight billion in the 2020s, with more people expected in sub-Saharan Africa.

Earth gives us things we need. Non-renewable resources like fossil fuels take millions of years to form. Humans also use minerals, which can hurt the environment. Plants and animals give us food, wood, medicine, and clean air. Land and water are important for growing food and building homes.

Humans have changed Earth's environment. Burning fossil fuels has added greenhouse gases, making Earth warmer, called global warming. This has made glaciers melt and raised sea levels. Scientists say there are limits to how much humans can change Earth without causing problems.