Amazing Facts About Our Earth: A Verified Tour of Our Home Planet

Short answer

• Earth is the only planet in our solar system known to have life, and the only one with liquid water on its surface, according to NASA.
• Its English name is unusual: unlike the other planets, it is not named after a Greek or Roman god. The name comes from Old English and Germanic words meaning "the ground."
• About 71 percent of Earth's surface is covered by ocean, and the ocean holds about 97 percent of Earth's water. Only about 2.5 percent of Earth's water is freshwater.
• Earth is about 4.54 billion years old, based on radiometric dating work reported by the USGS, and life on Earth began about 3.8 billion years ago, according to NASA.
• Earth's longest mountain range is underwater, its inner core is as hot as about 5,400 degrees Celsius, and its Moon is slowly drifting away at about 3.8 centimeters per year.
• Much of Earth remains unmapped in detail. NOAA notes that only a small share of the seafloor has been mapped by ships, and National Geographic Education reports that more than 80 percent of the ocean has never been mapped, explored, or even seen by humans.

Earth is the planet we know best, and it is also the planet that keeps surprising us. We live on its surface, drink its water, breathe its air, and watch its weather change by the hour, yet some of its most striking facts only become clear when the whole planet is measured at once: how much of it is ocean, how hot its center is, how old its rocks are, and how little of its seafloor has ever been mapped in detail.

This article gathers those facts in one place, and it checks each one. Every figure below comes from a named institutional source, mainly NASA, NOAA, the US Geological Survey (USGS), or the World Meteorological Organization (WMO). Where a figure is an estimate, or where different sources measure the same thing in different ways, the article says so. Six topics that already have their own Amberaisle articles are deliberately left out here, or mentioned only in passing: the distance from Earth to the Sun, the layers of the atmosphere, how many Earths could fit inside the Sun, Earth’s circumference, Earth’s electromagnetic field, and what would happen if Earth stopped spinning. Those articles are listed as related reading at the end, so this overview can stay broad without repeating them.

1. A Name That Means the Ground

Every other planet in our solar system carries the name of a god or goddess from Greek or Roman mythology. Earth does not. NASA explains that Earth’s English name comes from Old English and Germanic words, and that it simply means “the ground.” The name itself is about 1,000 years old.

That plain name fits the way people experienced the planet for most of history. Long before anyone saw Earth from space, or measured its size, the ground underfoot was the most familiar thing in the world. It was the soil for crops, the floor for houses, and the surface for every journey. The planet was named for what people could touch, not for a distant god.

Of course, “Earth” is only the English name. NASA notes that people speak thousands of languages, and that the planet has many names in those languages. The Roman goddess of Earth was Tellus, and the Greek goddess was Gaia, names that still appear in science: words such as “geology” and “geography” trace back to Gaia. But the everyday English name stayed close to home.

2. Earth Is Not a Perfect Sphere

School globes and space photographs make Earth look like a perfect ball, but it is not exactly one. Earth’s shape is best described as an oblate spheroid, which means it is slightly flattened at the poles and slightly bulging at the equator. The effect comes from Earth’s rotation: as the planet turns, material is thrown slightly outward at the equator, the way a spinning ball of soft dough flattens and widens.

The difference is small compared with the size of the whole planet, which is why it is invisible in most photographs. It still matters for practical work. Satellite measurements, maps, and coordinate systems all have to account for the fact that the distance from Earth’s center to the equator is greater than the distance from its center to a pole. A perfect sphere is a useful simplification for a classroom globe. For precise measurement, scientists use the flattened model instead.

NASA gives Earth’s equatorial diameter as 7,926 miles (12,756 kilometers). That single figure also tells a story about scale: Earth is large enough to hold entire mountain ranges, ocean basins, and weather systems, yet small enough, on the scale of the solar system, that its whole shape can be summed up in one diameter and one small correction for flattening.

3. The Fifth Largest Planet, and the Largest Rocky One

Earth ranks fifth in size among the eight planets of the solar system. NASA states this plainly in its Earth facts: Earth is only the fifth largest planet, behind the four giant planets, Jupiter, Saturn, Uranus, and Neptune. It is also, NASA notes, just slightly larger than nearby Venus.

At the same time, Earth is the biggest of the four planets closest to the Sun. Those four planets, Mercury, Venus, Earth, and Mars, are all made of rock and metal, and astronomers call them the terrestrial planets. Earth is the largest member of that rocky group. That combination, fifth overall but first among the rocky planets, explains a lot about Earth. It is big enough to hold onto a substantial atmosphere and to keep its interior hot, but it is not a gas giant. Its surface is solid rock, shaped by volcanoes, mountains, valleys, and oceans, rather than by layers of gas.

Size alone does not make a planet habitable. Venus is almost the same size as Earth, yet its surface is far too hot for liquid water oceans. Earth’s size is one part of its story. Its distance from the Sun, its atmosphere, and its water supply are the other parts, and it is the combination that sets Earth apart.

4. The Only Known Home of Life

NASA states the most important fact about Earth in a single sentence: Earth is the only place we know of that is inhabited by living things. Astronomers have studied the other planets and many moons in detail, and so far none has shown the same combination of liquid water, a breathable atmosphere, and stable temperatures that Earth has.

Water is the key. NASA notes that Earth is the only planet in our solar system with liquid water on its surface. That matters because life as we know it needs liquid water. Earth’s temperatures allow water to stay liquid for long periods, and its vast oceans provided a place for life to begin about 3.8 billion years ago, according to NASA. In other words, life did not just appear on Earth recently. It has been here for most of the planet’s history, changing and diversifying as continents moved, climates shifted, and new environments opened up.

Earth’s air is part of the same story. Near the surface, NASA reports, Earth’s atmosphere consists of about 78 percent nitrogen, about 21 percent oxygen, and about 1 percent other gases, including argon, carbon dioxide, and neon. Oxygen stays abundant in Earth’s air largely because living things, especially plants and ocean plankton, keep producing it. The atmosphere also shields the surface from much of the harmful radiation coming from the Sun, and it burns up most small meteoroids before they can reach the ground.

5. A Water Planet

If you could see Earth from far away, the first thing you would notice is its color. It is blue, because ocean covers about 71 percent of its surface. NASA gives that figure, and NOAA’s ocean data agree: the ocean covers 71 percent of Earth’s surface, with an area of about 139,400,000 square miles.

The ocean is also deep. NASA gives its average depth as about 2.3 miles (3.6 kilometers). NOAA gives the same average depth in its ocean dataset, at 2.3 miles. The drained seafloor would still show mountains, valleys, and plains.

The ocean also holds nearly all of Earth’s water. NASA states that the global ocean contains about 97 percent of Earth’s water. That leaves only about 2.5 percent as freshwater, according to USGS-based water distribution figures. Most of that freshwater is not in rivers and lakes. About 68.7 percent of freshwater is locked up in ice caps and glaciers, and about 30 percent is groundwater stored underground. Rivers, lakes, and other surface water together make up a tiny fraction of all freshwater, so the planet that looks blue from space is, for drinking and farming, a planet where usable water is surprisingly scarce.

6. Hidden Mountains and the Deepest Trench

Some of Earth’s most dramatic landscapes are ones almost nobody has ever seen, because they lie underwater. NASA reports that Earth’s longest mountain range is underwater, at the bottom of the Arctic and Atlantic oceans, and that it is four times longer than the Andes, Rockies, and Himalayas combined. NOAA names that range: the Mid-Atlantic Ridge, which runs through the middle of the Atlantic Ocean. It is a chain of volcanic mountains formed where tectonic plates pull apart, and new seafloor is created.

The deepest place in the ocean is just as striking. NOAA gives the depth of the Mariana Trench as 6.86 miles (11,033 meters). That is the deepest area in the ocean, and it lies in the western Pacific. NASA adds a comparison that helps make the scale vivid: Hawaii’s Mauna Kea volcano is taller from base to summit than Mount Everest, but most of Mauna Kea is underwater. If Everest were placed in the Mariana Trench, its peak would still be far below the ocean surface.

These underwater features are a good reminder that the familiar map of continents shows only part of Earth. The land we live on covers less than 30 percent of the surface. The rest is ocean, and the ocean floor has its own mountains, trenches, plains, and volcanoes. NASA notes that almost all of Earth’s volcanoes are hidden under these oceans.

7. A Restless, Moving Surface

Earth’s surface is not fixed in place. NASA explains that Earth’s lithosphere, which includes the crust and the upper mantle, is divided into huge plates that are constantly moving. The North American plate, for example, moves west over the Pacific Ocean basin at roughly the rate that fingernails grow. That sounds slow, and on a human timescale it is. Over millions of years, though, it adds up to oceans opening and closing, and continents drifting thousands of miles.

When plates grind past one another, ride up over one another, collide to make mountains, or split apart, the result is often an earthquake or a volcanic eruption. That is why earthquakes and volcanoes cluster along plate boundaries, such as the Ring of Fire around the Pacific. The movement also explains why the same kinds of fossils can be found on continents now separated by oceans: those continents were once joined, and they have since moved apart.

Plate movement also recycles Earth’s crust. Old seafloor sinks back into the mantle, and new seafloor forms at mid-ocean ridges such as the Mid-Atlantic Ridge. This slow recycling has gone on for billions of years, and it helps regulate Earth’s long-term climate by moving carbon between the surface and the interior.

8. What Lies Beneath: Core, Mantle, and Crust

NASA describes Earth as composed of four main layers: an inner core at the center, an outer core around it, a mantle, and a crust on the outside. Each layer has its own composition and behavior, and together they explain much of what happens on the surface.

The inner core is a solid sphere made of iron and nickel, about 759 miles (1,221 kilometers) in radius. NASA gives its temperature as high as 9,800 degrees Fahrenheit (5,400 degrees Celsius). That is comparable to the temperature at the surface of the Sun, and it is one of the most quoted facts about Earth: the center of our planet is as hot as the surface of a star. The inner core stays solid despite that heat because the pressure at Earth’s center is so great that the metal cannot melt.

Around the inner core lies the outer core, about 1,400 miles (2,300 kilometers) thick, made of iron and nickel fluids. Between the outer core and the crust lies the mantle, the thickest layer, about 1,800 miles (2,900 kilometers) thick, made of hot, viscous molten rock that NASA compares in consistency to caramel. The outermost layer, the crust, averages about 19 miles (30 kilometers) deep on land, and only about 3 miles (5 kilometers) from the seafloor to the top of the mantle under the oceans. We live on a thin skin, over a deep and very hot interior.

9. One Moon, Slowly Drifting Away

Earth has one permanent moon. NASA states this directly, and adds that Earth is the only planet in our solar system with only one moon. Other planets have none, or dozens. Earth’s single Moon is large relative to its planet, with a radius of 1,080 miles (1,738 kilometers), making it the fifth largest moon in the solar system, according to NASA.

NASA also explains how the Moon probably formed. When Earth was a young planet, a large chunk of rock smashed into it, displacing part of Earth’s interior. The resulting debris clumped together and formed the Moon. That giant impact story explains why the Moon’s composition is similar to Earth’s mantle, and why the early Moon was much closer to Earth than it is today.

The Moon is still moving. Measurements from lunar laser ranging, in which lasers are bounced off reflectors left on the Moon by Apollo astronauts, show that the Moon is spiraling away from Earth at about 3.8 centimeters per year. That rate comes from decades of laser ranging data reported in the geophysics literature, including a summary in Eos, the news magazine of the American Geophysical Union, which attributes the measurement to lunar laser ranging and links the retreat to Earth’s ocean tides. At 3.8 centimeters per year, the change is far too small to notice in a human lifetime, but over millions of years it adds up.

10. Deep Time: 4.54 Billion Years Old

Earth is very old, and scientists have measured its age with remarkable precision. The USGS reports that the age of Earth, based on radiometric dating of Earth and meteorite samples, is 4.54 billion years, with an uncertainty of about 50 million years. The method works like a clock: radioactive elements in rocks decay into stable elements at known rates, so measuring the ratio of parent to daughter elements in a sample gives its age. The best age for Earth does not come from dating a single rock, the USGS explains, but from considering Earth and meteorites as part of the same evolving system, since they formed together from the same early solar system material.

NASA gives a slightly rounded version of the same story: when the solar system settled into its current layout about 4.5 billion years ago, Earth formed as gravity pulled swirling gas and dust together to become the third planet from the Sun. Life, as noted above, began about 3.8 billion years ago. That means Earth existed for roughly 700 million years before the earliest life appeared, a long stretch in which the planet cooled, oceans formed, and the first continents began to take shape.

Deep time puts human history in perspective. Everything we call history, from the first cities to the first spaceflights, occupies a tiny fraction of the planet’s story. The rocks under our feet, by contrast, record billions of years of volcanoes, oceans, ice ages, and mass extinctions.

11. Air That Protects and Sustains

Earth’s atmosphere does more than provide air to breathe. NASA notes that it affects long-term climate and short-term local weather, shields the surface from much of the harmful radiation coming from the Sun, and protects the ground from meteoroids, most of which burn up in the atmosphere and are seen as meteors before they can strike the surface as meteorites.

That protection works silently every day. Dust and small rocks from space enter the atmosphere at high speed, and almost all of them are destroyed by friction before they reach the ground. Without an atmosphere, Earth would be pockmarked with craters the way the Moon is, and its surface would be exposed to far more solar radiation.

The atmosphere also keeps Earth’s temperatures in a range where liquid water can exist, by trapping some of the Sun’s heat. That warming is natural and necessary. The concern in recent decades is that human activities are adding extra heat-trapping gases, mainly carbon dioxide, faster than natural processes remove them. NASA notes that some features that make Earth hospitable to life are changing due to the ongoing effects of climate change.

12. Extremes of Cold and Heat

Earth’s temperature range is enormous. The lowest air temperature ever measured by a ground station, recognized by the WMO, is minus 89.2 degrees Celsius (minus 128.6 degrees Fahrenheit), recorded at Vostok Station in Antarctica on July 21, 1983. The WMO record, confirmed by the Arctic and Antarctic Research Institute, notes that the extreme cold resulted from the absence of solar radiation, clear skies, little vertical mixing, calm air over a long period, and the station’s high elevation, at 3,420 meters above sea level.

Satellites have measured even colder surface temperatures, about minus 93.2 degrees Celsius, over high ridges on the East Antarctic Plateau. Those satellite readings measure the temperature of the snow surface itself, not the air above it, so they are a different kind of measurement from the Vostok station record, and the two figures should not be mixed up.

At the hot end, the WMO-recognized highest air temperature is 56.7 degrees Celsius (134 degrees Fahrenheit), recorded at Death Valley in California on July 10, 1913. That record has been debated by researchers, because early twentieth century instruments and observing practices differ from modern ones, but it remains the accepted WMO figure. Together, the two records span about 146 degrees Celsius, from Antarctic winter cold to desert summer heat.

13. How Much of Earth Is Still Unexplored

The ocean is the biggest example. National Geographic Education reports that more than 80 percent of the ocean has never been mapped, explored, or even seen by humans. NOAA’s ocean dataset makes a related point: only a few percent of the seafloor has been mapped by ships, because ship-based sonar surveys cover narrow strips as vessels cross the ocean, and the ocean is vast.

Satellites help, but only up to a point. Satellite measurements of gravity can reveal large seafloor features, such as ridges and basins, but they cannot show fine detail. For that, ships must physically pass over every part of the seafloor with sonar, a slow and expensive task. That is why scientists sometimes say, loosely, that the surfaces of the Moon and Mars have been mapped in more detail than much of Earth’s own seafloor: orbiters can map a dry, airless surface from space far more easily than ships can map a deep ocean floor through water.

The same pattern holds on land, though to a lesser degree. Remote and rugged regions, deep caves, and dense forests still yield new species and new landscapes to researchers. Earth is the best studied planet we know, and it is also a planet where exploration is far from finished.

14. The View From Space: The Blue Marble

On December 7, 1972, the crew of Apollo 17 took a photograph that NASA archivist Mike Gentry has speculated is one of the most widely distributed images in history. NASA’s own record of the image, known as the Blue Marble, gives its date as December 7, 1972, and reproduces its original caption: a view of Earth as seen by the Apollo 17 crew traveling toward the Moon, extending from the Mediterranean Sea area to the Antarctic south polar ice cap. It was the first time an Apollo trajectory made it possible to photograph the south polar ice cap, and almost the entire coastline of Africa is clearly visible in the frame, along with the Arabian Peninsula, Madagascar, and parts of the Asian mainland.

The photograph mattered because it showed Earth as a whole, fully lit, floating in black space. Earlier photographs had shown parts of Earth, or Earth rising over the Moon’s horizon, but the Blue Marble showed the full disk: blue oceans, white clouds, brown and green land, and white ice at the south pole.

Earth has one more simple distinction worth noting: it has no rings. NASA lists this plainly among its Earth facts. Saturn, Jupiter, Uranus, and Neptune all have ring systems. Earth does not.

15. Why Earth Facts Still Change

A list of facts about Earth is never quite finished, because the measurements behind the facts keep improving. The age of Earth was refined as dating methods improved. The depth of the Mariana Trench has been remeasured with better sonar. Seafloor mapping coverage grows a little every year as new surveys are completed, and temperature records are re-examined when old logbooks are found or instruments are recalibrated.

That is a strength of Earth science. Each fact in this article rests on a measurement that other scientists can repeat and check. When a better measurement comes along, the fact gets updated. Readers should therefore ask of any list of amazing facts: who measured this, when, and how? If the answer is a named institution using a stated method, the fact is on solid ground. If no source is given, the fact is just a claim, however amazing it sounds.

Earth earns its amazement honestly. It is a rocky planet with liquid water oceans, a breathable atmosphere, a hot iron core, moving continents, a single retreating Moon, and life that has persisted for nearly four billion years. It is also a planet we have not finished exploring.

Frequently Asked Questions

What is the most amazing fact about Earth?

There is no single official answer, but NASA’s central fact is a strong candidate: Earth is the only planet in our solar system known to have life, and the only one with liquid water on its surface. If a single figure is preferred, the ocean figure runs it close: about 71 percent of Earth’s surface is ocean, and the ocean holds about 97 percent of Earth’s water.

Is Earth the largest planet?

No. Earth is the fifth largest planet in the solar system, according to NASA. It is, however, the largest of the four rocky planets closest to the Sun, and it is slightly larger than Venus.

Why is Earth called Earth?

The English name Earth comes from Old English and Germanic words meaning “the ground,” according to NASA. Unlike the other planets, it is not named after a Greek or Roman god or goddess. The name is about 1,000 years old.

How old is Earth?

Earth is about 4.54 billion years old, based on radiometric dating reported by the USGS, with an uncertainty of about 50 million years. NASA rounds the figure to about 4.5 billion years. Life on Earth began about 3.8 billion years ago, according to NASA.

How much of Earth is water?

About 71 percent of Earth’s surface is covered by ocean, and the ocean contains about 97 percent of Earth’s water, according to NASA. Only about 2.5 percent of Earth’s water is freshwater, and most of that freshwater is locked in ice caps and glaciers or stored as groundwater.

What is the deepest place on Earth?

The deepest place in the ocean is the Mariana Trench, which NOAA gives as 6.86 miles (11,033 meters) deep. It lies in the western Pacific Ocean. The deepest places on land are far shallower than the ocean trenches.

Does Earth have rings like Saturn?

No. NASA states plainly that Earth has no rings. Its appearance from space comes from its oceans, clouds, continents, and polar ice, not from a ring system.

How much of the ocean has been explored?

National Geographic Education reports that more than 80 percent of the ocean has never been mapped, explored, or even seen by humans. NOAA notes that only a small share of the seafloor has been mapped by ships. Satellite gravity data can show large seafloor features, but fine detail still requires ship-based sonar surveys.

Is the Moon moving away from Earth?

Yes, slowly. Lunar laser ranging measurements, bouncing lasers off reflectors left on the Moon by Apollo astronauts, show the Moon spiraling away at about 3.8 centimeters per year. The change is far too small to notice in a lifetime, but it is measurable with modern instruments.

Keep reading: What Is the Hydrosphere?

Sources & references

• NASA Science, Facts About Earth (science.nasa.gov): planet ranking, biggest terrestrial planet, name origin, liquid water on the surface, life beginning about 3.8 billion years ago, equatorial diameter, one moon, Moon formation and radius, formation about 4.5 billion years ago, four layers, inner core temperature and composition, outer core and mantle thickness, crust depth, ocean coverage and average depth, ocean share of Earth's water, longest underwater mountain range, Mauna Kea taller than Everest from base to summit, plate movement and earthquakes, atmosphere composition and meteoroid protection, no rings.
• NOAA, Science On a Sphere, Ocean Drain dataset (sos.noaa.gov): ocean coverage of 71 percent, ocean area, average depth of 2.3 miles, Mariana Trench depth of 6.86 miles (11,033 meters), Mid-Atlantic Ridge as the longest mountain range, only a small share of the seafloor mapped by ships.
• US Geological Survey (USGS), Age of the Earth (pubs.usgs.gov): Earth age of 4.54 billion years from radiometric dating of Earth and meteorite samples, with the method explained as considering Earth and meteorites as part of the same evolving system.
• US Geological Survey water distribution figures, as summarized in USGS-based references: about 97.5 percent of Earth's water in oceans, about 2.5 percent freshwater, about 68.7 percent of freshwater in ice caps and glaciers, about 30 percent as groundwater.
• World Meteorological Organization (WMO), Archive of Weather and Climate Extremes (wmo.int): lowest air temperature of minus 89.2 degrees Celsius (minus 128.6 degrees Fahrenheit) at Vostok Station, Antarctica, on July 21, 1983; highest air temperature of 56.7 degrees Celsius (134 degrees Fahrenheit) at Death Valley, California, on July 10, 1913, as reported in WMO-recognized records.
• National Geographic Education, Ocean resource (education.nationalgeographic.org): ocean coverage of about 71 percent, about 97 percent of Earth's water in the ocean, more than 80 percent of the ocean never mapped, explored, or seen by humans, average ocean depth of 3,720 meters.
• Eos, American Geophysical Union, Seeing the Light (eos.org): lunar laser ranging measurement of the Moon moving away from Earth at 3.8 centimeters per year, attributed to ocean tides, based on reflectors left by Apollo missions.
• NASA Science, The Blue Marble (science.nasa.gov): photograph taken December 7, 1972, by the Apollo 17 crew, original caption describing the view from the Mediterranean Sea area to the Antarctic south polar ice cap, and the first Apollo photograph of the south polar ice cap.