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- Earth, the only planet known to support life, offers liquid water, an oxygen-rich atmosphere, and protection from the Sun’s harmful radiation.
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Earth is the third planet from the Sun and the only astronomical object known to harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all of Earth's water is contained in its global ocean, covering 70.8% of Earth's crust.
- Namesake. The name Earth is at least 1,000 years old. All of the planets, except for Earth, were named after Greek and Roman gods and goddesses. However, the name Earth is a Germanic word, which simply means “the ground.”
- Potential for Life. Earth has a very hospitable temperature and mix of chemicals that have made life abundant here. Most notably, Earth is unique in that most of our planet is covered in liquid water, since the temperature allows liquid water to exist for extended periods of time.
- Size and Distance. With an equatorial diameter of 7926 miles (12,760 kilometers), Earth is the biggest of the terrestrial planets and the fifth largest planet in our solar system.
- Orbit and Rotation. As Earth orbits the Sun, it completes one rotation every 23.9 hours. It takes 365.25 days to complete one trip around the Sun. That extra quarter of a day presents a challenge to our calendar system, which counts one year as 365 days.
3 days ago · Earth, third planet from the Sun and the fifth largest planet in the solar system in terms of size and mass. Its single most outstanding feature is that its near-surface environments are the only places in the universe known to harbour life. It is designated by the symbol ♁.
- Earth is the third planet from the Sun and the fifth largest planet in the solar system in terms of size and mass. Its near-surface environments ar...
- Earth is located in the Orion-Cygnus Arm, one of the four spiral arms of the Milky Way, which lies about two-thirds of the way from the centre of t...
- Earth’s name in English, the international language of astronomy, derives from Old English and Germanic words for ground and earth, and it is the o...
- Earth and the other planets in the solar system formed about 4.6 billion years ago. The early Earth had no ozone layer and no free oxygen, lacked o...
- Viewed from another planet, Earth would appear bright and bluish in colour. In latitudinal belts, swirling white cloud patterns of midlatitude and...
- Earth's orbit. While Earth orbits the sun, the planet is simultaneously spinning on an imaginary line called an axis that runs from the North Pole to the South Pole.
- Earth's formation and evolution. Scientists think Earth was formed at roughly the same time as the sun and other planets some 4.6 billion years ago when the solar system coalesced from a giant, rotating cloud of gas and dust known as the solar nebula.
- Internal structure. Earth's core is about 4,400 miles (7,100 km) wide, slightly larger than half the Earth's diameter and about the same size as Mars' diameter.
- Magnetic field. Earth's magnetic field is generated by currents flowing in Earth's outer core. The magnetic poles are always on the move, with the magnetic North Pole accelerating its northward motion to 24 miles (40 km) annually since tracking began in the 1830s.
- Overview
- Our dance around the sun
- Many layers, many features
- Protective fields and gases
- Spaceship Earth
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Our home planet provides us with life and protects us from space.
Earth, our home planet, 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.
With a radius of 3,959 miles, Earth is the fifth largest planet in our solar system, 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.”
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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.
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.
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.
Like Venus and Mars, Earth has mountains, valleys, and volcanoes. But unlike its rocky siblings, almost 70 percent of Earth's surface is covered in oceans of liquid water that average 2.5 miles deep. These bodies of water contain 97 percent of Earth's volcanoes and the mid-ocean ridge, a massive mountain range more than 40,000 miles long.
Earth's crust and upper mantle are divided into massive plates that grind against each other in slow motion. As these plates collide, tear apart, or slide past each other, they give rise to our very active geology. Earthquakes rumble as these plates snag and slip past each other. Many volcanoes form as seafloor crust smashes into and slides beneath continental crust. When plates of continental crust collide, mountain ranges such as the Himalaya are pushed toward the skies.
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.
Earth is the planet we have the best opportunity to understand in detail—helping us see how other rocky planets behave, even those orbiting distant stars. As a result, scientists are increasingly monitoring Earth from space. NASA alone has dozens of missions dedicated to solving our planet's mysteries.
At the same time, telescopes are gazing outward to find other Earths. Thanks to instruments such as NASA's Kepler Space Telescope, astronomers have found more than 3,800 planets orbiting other stars, some of which are about the size of Earth, and a handful of which orbit in the zones around their stars that are just the right temperature to be potentially habitable. Other missions, such as the Transiting Exoplanet Survey Satellite, are poised to find even more.
SOURCES
NASA Science Solar System Exploration - Earth
NOAA Ocean Explorer - Mid-Ocean Ridge
NOAA Climate - Climate Change
Learn about Earth's features, layers, atmosphere, and climate, and how it differs from other planets. Earth is the only place in the known universe confirmed to host life and liquid water on its surface.
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Oct 11, 2024 · Earth is a terrestrial planet. It is small and rocky. Earth's atmosphere is the right thickness to keep the planet warm so living things like us can be there. It’s the only planet in our solar system we know of that supports life. It is mostly nitrogen, and it has plenty of oxygen for us to breathe.
Learn about Earth's unique features, history, and challenges from the only organization dedicated to the exploration of space for the benefit of humanity and planetary protection.
