Science · Earth & Space Science

Planet Earth

Reading comprehension passage and printable worksheet about planet Earth — its structure, atmosphere, water, and place in the solar system — for grades 3–6.

Reading Passage

Planet Earth

Earth is the third planet from the sun and the only known planet in the universe to support life. It formed about 4.5 billion years ago from a cloud of gas and dust swirling around the young sun. Earth is the fifth largest planet in our solar system, with a diameter of about 12,742 kilometers. It orbits the sun once every 365.25 days, which gives us our calendar year.

Earth is made up of distinct layers. The outer layer is the crust — the solid rock surface we live on. Below the crust is the mantle, a thick layer of hot rock that moves slowly over millions of years. At the center is the core, divided into a liquid outer core and a solid inner core made mostly of iron and nickel. The movement of the liquid outer core generates Earth’s magnetic field, which protects life from harmful solar radiation.

Earth’s surface is covered about 71 percent by water. The oceans play a crucial role in regulating Earth’s climate by absorbing heat from the sun and distributing it around the planet. The water cycle — evaporation, condensation, and precipitation — constantly moves water between the oceans, atmosphere, and land. Freshwater rivers, lakes, and groundwater make up only a small fraction of Earth’s total water.

Earth is surrounded by a layer of gases called the atmosphere. The atmosphere is made up mostly of nitrogen (78%) and oxygen (21%), with small amounts of other gases including carbon dioxide and water vapor. The atmosphere protects life on Earth by blocking harmful ultraviolet radiation, regulating temperature, and providing the air we breathe. Without the atmosphere, Earth’s surface would be either frozen or scorched.

Earth’s surface is constantly changing due to the movement of tectonic plates — large sections of the crust that float on the mantle. The collision and separation of these plates cause earthquakes, volcanic eruptions, and the formation of mountains and ocean trenches. Over millions of years, the continents have moved across the surface of Earth in a process called continental drift. Earth is a dynamic, ever-changing planet.

Printable Worksheet

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