# Quick Geography Facts About Planet Earth

Caitlin Dempsey

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Listed here are some quick geography facts about Earth as a planet. Planet Earth is the third planet from the Sun and the fifth largest planet in our solar system.

The word “Earth” derives from a Germanic word meaning “the ground”.

## Age

The Earth is estimated to be 4.6 billion years old.

## Mass

The mass of the Earth is calculated to be 5.976 Ã—1024 kilograms.  The unit of mass equivalent to that of the Earth is referred to as the Earth mass (MâŠ•).

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The mass of the Earth is not evenly distributed. Different portions of the world have more or less mass than others due to varying surface topography and the constant movement of water.

## Volume

The volume of the earth is about 1,083,210,000,000 km3 (2.5988Ã—1011 cu mi).

The Earth’s radius is 3,959 miles (6,371 kilometers) which makes it the largest terrestrial planet and the fifth largest planet in the solar system.

Polar diameter 12,713.54 km;  Equatorial diameter 12,756,32 km; Polar circumference 40,008.00 km and Equatorial circumference 40,075.16 km.

## Mean Density

The mean density of the earth is 5.518 kg/liters.

## Earth’s Gravity

The Earth’s gravity actually increases slightly as you move closer to the core, peaking at the core-mantle boundary due to an increase in core material density.

On the surface of the Earth, the force of gravity is also not consistent.

In this visualization of the Earth’s gravity created by NASA, areas with strong gravity are represented by warm colors (red, orange, yellow). Areas with weak gravity are represented by cool colors (green, blue).

Mountain ranges with a large concentration of mass, such as the Himalayas, have a strong gravitational field. Ocean trenches, such as the Mariana Trench, have a weak gravitational field because to the low concentration of mass.

## Shape

The earth is not a perfect sphere.  The shape of the earth is an oblate spheroid or a geoid.

## Area

The total surface area of Earth is 509,7000,000 sq. km. Earth’s surface is mostly covered by water. Land area about 148,400,000 km (about 29 per cent of the total area); Water area about 361,300,000 sq. km. (about 71 per cent of the total surface area).

## Distance from the Sun

On average, the Earth is about 93 million miles (150 million kilometers) from the Sun. The distance from the Earth to the Sun is known as one astronomical unit (AU). It takes light eight minutes to travel from the Sun to the Earth.

The Earth is at its closest point (91.5 million miles away) to the Sun in early January, known as the perihelion. In early July, the Earth is at its farthest point from the Sun (94.5 million miles away), known as the aphelion.

The Earth makes one rotation every 23.9 hours. It takes 365.25 days to revolve around the Sun. Every four years, Leap Day is added to adjust for the slight difference between the calendar year and the amount of days it takes the Earth to revolve around the Sun.

## Moon

The Earth is the only planet that has only one moon.

## The Most Distributed Photo of Earth

The Blue Marble is the nickname given to the photo taken by an astronaut onboard Apollo 17 because of its similarity to a child’s marble. The photograph captured a view of Africa, Antarctica, and the Arabian Peninsula. The 1972 Tamil Nadu cyclone, which has brought flooding and high winds to India on December 5, can be seen in the bottom left of the image.

The Blue Marble is one of the most distributed images of Earth. The actual photographer is unknown because all three astronauts, astronaut Eugene A. Cernan, commander; astronaut Ronald E. Evans, command module pilot; and scientist-astronaut Harrison H. Schmitt, lunar module pilot, were taking pictures of the Earth during the time period that this photo was taken.

The image of Earth is fully illuminated as the Sun was behind the planet when the picture was taken.

The image most people see of the Blue Marble has been cropped and rotate. The original image had a south orientation with the South polar caps at the top of the photograph, an orientation that would be confusing to many people.

## Overview Effect

The Overview Effects a shift in awareness by astronauts seeing Earth from outer space and see the planet as a “tiny, fragile ball of life.” The term was coined by author Frank White in 1987 in his book, The Overview Effect â€” Space Exploration and Human Evolution

The thing that really surprised me was that it [Earth] projected an air of fragility. And why, I donâ€™t know. I donâ€™t know to this day. I had a feeling itâ€™s tiny, itâ€™s shiny, itâ€™s beautiful, itâ€™s home, and itâ€™s fragile.

Michael Collins, Apollo 11

## Motion of the Earth

Rotation (spinning motion on polar axis), once every 23 hours 56 minutes and 4.09 seconds.

Revolution (around the sun), once every 365 days, 6 hours, 9 minutes and 9.54 seconds.

## Surface Features

Highest point on land – Mt Everest 8,848 m above the sea level.

Lowest area on land- shore of Dead Sea (399 m below sea level). Mean height of land 756 m.

## Ocean Depths

Deepest area – Mariana Trench in Pacific Ocean south-west of Guam (11,033 m below the sea surface). Average depth of oceans 3,730 m.

## Chemical make up of the Earthâ€™s Crust

(percent by weight): oxygen 46.6, silicon 27.7, aluminium 8.1, iron 5.0, calcium 3.6, sodium 2.8, potassium 2.6, magnesium 2.0 and other elements 1.6.

## Temperatures

Mean Surface Temperature       : 14Â°C

Highest temperature of 70.7 degrees C (159 degrees F) at Lut Desert measured in 2005. Related: World Highest Minimum Temperature Record Broken, and Many Follow

Lowest temperature measured at minus 136 F (minus 93.2 C) on August 10, 2010 in pockets between Dome Argus and Dome Fuji, two summits on the ice sheet known as the East Antarctic.

## Inclination

Inclination of the Polar Axis to the Orbital Plane        :  23 deg. 26 min. 59 second.

## Orbital Speed

Orbital Speed    :  29.8 km/s

## About the Sun Mean Distance

From the Sun : 149,598,500 km (one astronomical unit). The maximum distance at the time of aphelion between July 2 and 5 is about 152 million km and the minimum distance at perihelion between January 2 and 5 is about 147 million km.

## Encyclopedia of Earth

The Encyclopedia of Earth is an online resource with the objective of providing accurate information on a wide range of information relating to the Earth.  Made up of a “diverse group of respected scientists and educators, and the organizations, agencies, and institutions for which they work“, the articles are written in a non-technical way.  The site features a “Where in the World” button which allows the visitor access to articles by location.