The Earth 🌍

December 23, 2020

The Earth 🌍

Earth is the only planet which we can live because its atmosphere which is made mostly of nitrogen and has plenty of oxygen for us to breathe. The atmosphere also protects us from incoming meteoroids, most of which break up in our atmosphere before they can strike the surface as meteorites.

Since we live here, you might think we know all there is to know about Earth. Not at all, actually! We have a lot we can learn about our home planet. Right now, there are many satellites orbiting Earth taking pictures and measurements. This is how we can learn more about weather, oceans, soil, climate change, and many other important topics.

It is the home for Human being , is a world unlike any other. The third planet from the sun, Earth is the only place in the known universe confirmed to host life. probably not😏If you want me write about this topic write me in the comments section we continue..

With a radius of 3,959 miles, Earth is the fifth largest planet in our solar system, beating Venus, Mercury, Pluto, and Mars with this radius, and it's the only one known for sure to have liquid water on its surface. Earth is also unique in terms of monikers. Every other solar system planet was named for a Greek or Roman deity, but for at least a thousand years, some cultures have described our world using the Germanic word “earth,” which means simply “the ground.”

Our dance around the sun

Earth orbits the sun once every 365.25 days. Since our calendar years have only 365 days, we add an extra leap day every four years to account for the difference.

Earth during an eclipse from National Geographic

Though we can't feel it, Earth zooms through its orbit at an average velocity of 18.5 miles a second. During this circuit, our planet is an average of 93 million miles away from the sun, a distance that takes light about eight minutes to traverse. Astronomers define this distance as one astronomical unit (AU), a measure that serves as a handy cosmic yardstick.

Earth rotates on its axis every 23.9 hours, defining day and night for surface dwellers. This axis of rotation is tilted 23.4 degrees away from the plane of Earth's orbit around the sun, giving us seasons. Whichever hemisphere is tilted closer to the sun experiences summer, while the hemisphere tilted away gets winter. In the spring and fall, each hemisphere receives similar amounts of light. On two specific dates each year—called the equinoxes—both hemispheres get illuminated equally.

Many layers, many features

About 4.5 billion years ago, gravity coaxed Earth to form from the gaseous, dusty disk that surrounded our young sun. Over time, Earth's interior—which is made mostly of silicate rocks and metals—differentiated into four layers.

At the planet's heart lies the inner core, a solid sphere of iron and nickel that's 759 miles wide and as hot as 9,800 degrees Fahrenheit. The inner core is surrounded by the outer core, a 1,400-mile-thick band of iron and nickel fluids. Beyond the outer core lies the mantle, a 1,800-mile-thick layer of viscous molten rock on which Earth's outermost layer, the crust, rests. On land, the continental crust is an average of 19 miles thick, but the oceanic crust that forms the seafloor is thinner—about three miles thick—and denser.

Protective fields and gases

Earth's atmosphere is 78 percent nitrogen, 21 percent oxygen, and one percent other gases such as carbon dioxide, water vapor, and argon. Much like a greenhouse, this blanket of gases absorbs and retains heat. On average, Earth's surface temperature is about 57 degrees Fahrenheit; without our atmosphere, it'd be zero degrees. In the last two centuries, humans have added enough greenhouse gases to the atmosphere to raise Earth's average temperature by 1.8 degrees Fahrenheit. This extra heat has altered Earth's weather patterns in many ways.

The atmosphere not only nourishes life on Earth, but it also protects it: It's thick enough that many meteorites burn up before impact from friction, and its gases—such as ozone—block DNA-damaging ultraviolet light from reaching the surface. But for all that our atmosphere does, it's surprisingly thin. Ninety percent of Earth's atmosphere lies within just 10 miles of the planet's surface.

Next will be Mars