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How Big Is Earth?

Our planet as seen from space.
Our planet as seen from space. (Image credit: NASA/JPL)

Earth, the third planet from the sun, is the fifth-largest planet in the solar system; only the gas giants Jupiter, Saturn, Uranus and Neptune are bigger. Earth is the largest of the terrestrial planets of the inner solar system, bigger than Mercury, Venus and Mars. But how big is Earth, exactly?

Radius, diameter and circumference

The radius of Earth at the equator is 3,963 miles (6,378 kilometers), according to NASA's Goddard Space Flight Center in Greenbelt, Maryland. However, Earth is not quite a sphere. The planet's rotation causes it to bulge at the equator. Earth's polar radius is 3,950 miles (6,356 km) — a difference of 13 miles (22 km).

Using those measurements, the equatorial circumference of Earth is about 24,901 miles (40,075 km). However, from pole to pole — the meridional circumference — Earth is only 24,860 miles (40,008 km) around. Our planet's shape, caused by the flattening at the poles, is called an oblate spheroid.

Those numbers make Earth just slightly bigger than Venus, whose equatorial radius is about 3,761 miles (6,052 km). Mars is much smaller than both Earth and Venus, with an equatorial radius of just 2,110 miles (3,396 km).

But Earth and the other rocky planets are much smaller than the gas giants. For example, more than 1,300 Earths could fit inside Jupiter.

Related: What's the speed of Earth around the sun?

Density, mass and volume

Earth's density is 5.513 grams per cubic centimeter, according to NASA. Earth is the densest planet in the solar system because of its metallic core and rocky mantle. Jupiter, which is 318 more massive than Earth, is less dense because it is made primarily of gases, such as hydrogen.

Earth's mass is 6.6 sextillion tons (5.9722 x 1024 kilograms). Its volume is about 260 billion cubic miles (1 trillion cubic kilometers).

The total surface area of Earth is about 197 million square miles (510 million square km). About 71% of our planet is covered by water and 29% by land. For comparison, the total surface area of Venus is roughly 178 million square miles (460 million square km) , and that of Mars is about 56 million square miles (144 million square km)

Highest and lowest points

Mount Everest is the highest place on Earth above sea level, at 29,032 feet (8,849 meters), but it is not the highest point on Earth — that is, the place most distant from the center of the Earth. That distinction belongs to Mount Chimaborazo in the Andes Mountains in Ecuador, according to the U.S. National Oceanic and Atmospheric Administration (NOAA). Although Chimaborazo is about 10,000 feet (3,048 m) shorter (relative to sea level) than Everest, this mountain is about 6,800 feet (2,073 m) farther into space because of the equatorial bulge.

Everest and Chimborazo are nowhere near the tallest mountains in the solar system, however. The peak rising from Rheasilvia Crater on the asteroid Vesta, for example, is about 14 miles (22.5 km) tall. Mars' huge Olympus Mons volcano is nearly as high, at 13.6 miles (21.9 km), and it covers an area the size of the state of Arizona.

The lowest point on Earth is Challenger Deep in the Mariana Trench in the western Pacific Ocean, according to NOAA. It reaches down about 36,200 feet (11,034 m) below sea level.

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