What Is Earth?

    Published: 06-16-2009
    Views: 14,306
    Science expert Emerald Robinson explains everything about planet Earth and its location in the solar system.

    Emerald Robinson: In this "What Is" video, we're going to take a closer look at the planet we all call home.

    Planet Earth is home to over 7 billion people and nearly 9 million different species of plants, animals and insects. Seen from space, it's a majestic blue and green marble. But this picturesque planet has a treasure trove of interesting facts waiting to be discovered.

    Long before man took photos of Earth from space, people knew that the planet was round. How you might ask. One way was to watch a ship sailing off into the horizon. It would continue to get smaller and smaller until only the tallest point of its sail was visible. This meant that instead of falling off an edge, it was slowly curving away from the observer, a sure sign that Earth wasn't flat.

    Of course we now know that the Earth is part of a solar system where multiple planets orbit around a bright star called the Sun. Earth is the third planet from the Sun, making if one of the inner planets.

    The inner planets are relatively small, dense, and rocky. In contrast, the outer planets in the solar system are giant balls of swirling gas. To put Earth's size in perspective, the largest planet in our solar system, Jupiter is 1,000 times the size of Earth. And the Sun is about 1,000 times bigger than Jupiter.

    The Earth can be separated into different layers that function in harmony to support life as we know it. The Lithosphere is the top most layer of Earth's crust. It includes mountains, valleys, continents, and all of the rock beneath the oceans.

    The Hydrosphere is all of the water on Earth, including the 75% of the Earth that is covered by ocean. The Atmosphere is the thin layer of air that surrounds the Earth. It is made mostly of nitrogen and oxygen. Water and oxygen are crucial to life as we know it.

    The Biosphere describes all the living organisms on Earth. This self-regulating ecosystem supports life in even the remotes regions of the planet. As you can see, we live on a unique planet and each of its layers performs a crucial role in supporting you, me and the millions of other species that inhabit it.