Earth is the third planet from the Sun and the largest of the four inner rocky planets in our Solar System. It is the only known planet to harbor life. Unlike the other planets, Earth has a unique set of characteristics ideally suited to supporting life as we know it. It is neither too hot, nor too cold. Earth’s atmosphere includes just the right amount of gases that trap heat from the Sun, resulting in a moderate climate suitable for water to exist in liquid form. The atmosphere also helps block harmful radiation from the Sun.
Earth is made up of complex, interactive systems that create a constantly changing world. The Earth consists of a thin atmosphere consisting of a mixture of gases, primarily molecular nitrogen (78 percent) and molecular oxygen (21 percent), the hydrosphere (all water on Earth), the lithosphere, mantle, and core. Water in the form of the oceans covers approximately 70% of the earth’s surface. The remaining 30% is land. Earth’s surface is traditionally subdivided into seven continental masses: Africa, Antarctica, Asia, Australia, Europe, North America, and South America. These continents are surrounded by four major bodies of water: the Arctic, Atlantic, Indian, and Pacific oceans.
The earth’s crust is about 5 miles thick under the oceans and about 25 miles thick under the continents. Beneath the crust is a sphere of hot rock and metal.
The earth never stops moving. It has three motions; it spins, it travels around the sun, and it moves through the Milky Way. We use the spinning and traveling to measure our days and years. The earth spins around it’s axis and makes it seem that the sun is moving from east to west. One day (23 hours, 56 minutes, and 4.091) is the time it takes for one spin.
The earth also travels around the sun. It takes 365 days, 6 hours, 9 minutes and 9.54 seconds for a full rotation and this is called a year. The earth travels 595 million miles around the sun at a speed of 66,600 miles per hour. The path the earth takes to move around the sun is called an orbit. The Milky Way also spins. It revolves around the center of the Galaxy at 155 miles per second.
Earth has one natural satellite, the Moon. The Moon orbits the Earth, completing one revolution in an elliptical path in 27 days 7 hr 43 min 11.5 sec. The Moon orbits the Earth because of the force of Earth’s gravity. However, the Moon also exerts a gravitational force on the Earth. Evidence for the Moon’s gravitational influence can be seen in the ocean tides. A popular theory suggests that the Moon split off from Earth more than 4 billion years ago when a large meteorite or small planet struck the Earth.
- Earth is estimated to be 3-5 Billion Years old
- Average Distance from the Earth to the Sun: 93,020,000 miles (149,669,180 km)
- Average Distance from the Earth to the Moon: 238,857 miles (384,403.1 km)
- The Earth weighs 6,588,000,000,000,000,000,000,000 tons
- The Earth’s molten iron core creates a magnetic field
- Earth is the only planet in the Solar System known to be geologically active
- Tallest Mountain on Earth from Base to Peak is Mauna Kea in Hawaii: 33,480 feet (rising to 13,796 feet above sea level) (10204 m; 4205 m)
- The Dead Sea has the lowest elevation on land: 1369 feet below sea level (417.27 m)
- The Mariana Trench is the deepest point in the Ocean: 35,840 feet (10924 m)
- Earth’s oceans are an average of 2 Miles deep
- Highest Temperature Recorded: 134°F (56.7°C) – Greenland Ranch in Death Valley, California, July 10, 1913
- Lowest Temperature Recorded: -128.5°F (-89.2°C) – Vostok, Antarctica, July 21, 1983
- The world is not round. It is an oblate spheroid, flattened at the poles and bulging at the equator.
- The Earth’s atmosphere extends out to 10,000 km
- 1,000 tons of space debris rains down on Earth every year
|mean distance from Sun||149,598,262 km (1.0 AU)|
|eccentricity of orbit||0.0167|
|inclination of orbit to ecliptic||0.000°|
|Earth year (sidereal period of revolution)||365.256 days|
|mean orbital velocity||29.78 km/sec|
|equatorial radius||6,378.14 km|
|polar radius||6,356.78 km|
|surface area||510,064,472 km2|
|mass||5.972 × 1024 kg|
|mean density||5.51 g/cm3|
|mean surface gravity||980 cm/sec2|
|escape velocity||11.2 km/sec|
|rotation period (Earth sidereal day)||23.9345 hr (23 hr 56 min 4 sec)
of mean solar time
|Earth mean solar day||24.0657 hr (24 hr 3 min 57 sec)
of mean sidereal time
|inclination of Equator to orbit||23.44°|
|magnetic field strength at Equator||0.3 gauss (but weakening)|
|dipole moment||7.9 × 1025 gauss/cm3|
|tilt angle of magnetic axis||11.5°|
|atmospheric composition (by volume)||molecular nitrogen, 78%; molecular oxygen, 21%; argon, 0.93%; carbon dioxide, 0.0395% (presently rising); water, about 1% (variable)|
|mean surface pressure||1 bar|
|mean surface temperature||288 K (59 °F, 15 °C)|
|number of known moons||1 (the Moon)|