The Earth is the planet we live on, the third planet from the Sun in our solar system. It's a massive sphere of rock spinning through space, covered with oceans, continents, forests, deserts, and ice caps. Earth is the only planet we know of that supports life, with millions of species of plants, animals, and other organisms thriving on its surface and in its waters.

When you look up at the night sky and see the Moon and stars, remember that you're standing on Earth looking out into space. Astronauts who have seen Earth from orbit describe it as a beautiful blue and white marble floating in darkness, with swirling clouds and sparkling oceans.

The word earth (lowercase) also means soil or dirt, the brown stuff you dig in when planting a garden. This meaning connects to the planet's name: the ground beneath our feet is literally part of Earth itself. When a farmer works the earth, she's tilling the soil to prepare it for planting.

You might hear someone say they want to know “why on earth” something happened, using earth as an intensifier meaning “in the world.” And when something costs “the earth,” it means it's extremely expensive, as if you'd have to trade the whole planet to pay for it.