Earth, our home planet, is the only planet in its solar system known to harbor life. All of the things we need to survive are provided under a thin layer of atmosphere that separates us from the uninhabitable void of space.

Earth is made up of complex, interactive systems that are often unpredictable. Air, water, land, and life—including humans—combine forces to create a constantly changing world.

EARTH: FAST FACTS

• Earth is the third planet from the sun and the fifth largest in the solar system.
• Earth is 92,955,820 miles (149,597,891 kilometers) away from the sun.
• At 7,917.5 miles (12,742 km), Earth's diameter is just a few hundred kilometers larger than that of Venus.
• The four seasons are a result of Earth's axis of rotation being tilted more than 23 degrees.
• The length of a year on Earth is 365 days, 6 hours, and 16 minutes.
• The length of a day on Earth is 23 hours and 56 minutes.
• Oceans at least 2.5 miles (4 kilometers) deep cover nearly 70 percent of Earth's surface.
• The minimum weather temperature on Earth is -126 degrees Fahrenheit (-87.8 degrees Celsius) and the maximum weather temperature on Earth is 136 degrees Fahrenheit (57.8 degrees Celsius).
• Fresh water exists in the liquid phase only within a narrow temperature span (32 to 212 degrees Fahrenheit/0 to 100 degrees Celsius). This temperature span is especially narrow when contrasted with the full range of temperatures found within the solar system (from -400 to 900 degrees Farenheit/-300 to 500 degrees Celcius).
• The presence and distribution of water vapor in the atmosphere is responsible for much of Earth's weather.

This article is about the planet itself. For its human aspects, see World. For other uses, see Earth (disambiguation).

Earth 

The Blue Marble photograph of Earth, taken during the Apollo 17lunar mission in 1972
Orbital characteristics
Epoch J2000[n 1]
Aphelion	152100000 km[n 2] (94500000 mi; 1.017 AU)
Perihelion	147095000 km[n 2] (91401000 mi; 0.98327 AU)
Semi-major axis	149598023 km[1] (92955902 mi; 1.00000102 AU)
Eccentricity	0.0167086[1]
Orbital period	365.256363004 d[2] (1.00001742096 yr)
Average orbital speed	29.78 km/s[3] (107200 km/h; 66600 mph)
Mean anomaly	358.617°
Inclination	7.155° to the Sun's equator; 1.57869°[4] to invariable plane; 0.00005° to J2000 ecliptic
Longitude of ascending node	−11.26064°[3] to J2000 ecliptic
Argument of perihelion	114.20783°[3]
Satellites	1 natural satellite: the Moon 5 quasi-satellites >1 400 operational artificial satellites[5] >16 000 space debris[n 3]
Physical characteristics
Mean radius	6371.0 km (3958.8 mi)[6]
Equatorialradius	6378.1 km (3963.2 mi)[7][8]
Polar radius	6356.8 km (3949.9 mi)[9]
Flattening	0.0033528[10] 1/298.257222101 (ETRS89)
Circumference	40075.017 km equatorial (24901.461 mi)[8] 40007.86 km meridional (24859.73 mi)[11][12]
Surface area	510072000 km2 (196940000 sq mi)[13][14][n 4] 148940000 km2 land (57510000 sq mi; 29.2%) 361132000 km2 water (139434000 sq mi; 70.8%)
Volume	1.08321×1012 km3 (2.59876×1011 cu mi)[3]
Mass	5.97237×1024 kg (1.31668×1025 lb)[15] (3.0×10−6 M☉)
Mean density	5.514 g/cm3 (0.1992 lb/cu in)[3]
Surface gravity	9.807 m/s2 (1 g; 32.18 ft/s2)[16]
Moment of inertia factor	0.3307[17]
Escape velocity	11.186 km/s[3] (40270 km/h; 25020 mph)
Sidereal rotation period	0.99726968 d[18] (23h 56m 4.100s)
Equatorial rotation velocity	0.4651 km/s[19] (1674.4 km/h; 1040.4 mph)
Axial tilt	23.4392811°[2]
Albedo	0.367 geometric[3] 0.306 Bond[3]
Surface temp. min mean max Kelvin 184 K[20] 288 K[21] 330 K[22] Celsius −89.2 °C 15 °C 56.7 °C Fahrenheit −128.5 °F 59 °F (15 °C) 134 °F (57 °C)
Atmosphere
Surface pressure	101.325 kPa (at MSL)
Composition by volume	78.08% nitrogen (N2; dry air)[3] 20.95% oxygen (O2) 0.930% argon 0.0402% carbon dioxide[23] ~ 1% water vapor (climate-variable)

Earth is the third planet from the Sun and the only object in the Universe known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4 billion years ago.^[24][25][26] Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.^{[n 5]}

Earth's axis of rotation is tilted, producing seasonal variations on the planet's surface.^[27] The gravitational interactionbetween the Earth and Moon causes ocean tides, stabilizes the Earth's orientation on its axis, and gradually slows its rotation.^[28] Earth is the densest planet in the Solar System and the largest of the four terrestrial planets.

Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water, mostly by oceans.^[29] The remaining 29% is landconsisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, and a convecting mantle that drives plate tectonics.

Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphereand surface, leading to the proliferation of aerobic and anaerobic organisms. Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive.^[30][31] In the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species^[32] that ever lived on Earth are extinct.^[33][34] Estimates of the number of species on Earth today vary widely;^[35][36][37] most species have not been described.^[38] Over 7.4 billion humans live on Earth and depend on its biosphere and natural resources for their survival. Humans have developed diverse societies and cultures; politically, the world has about 200 sovereign states.