1 E5 m
Encyclopedia
A length of 100 kilometers (about 62 miles), as a rough amount, is relatively common in measurements on Earth and for some astronomical objects.
It is the altitude at which the FAI defines spaceflight
Spaceflight
Spaceflight is the act of travelling into or through outer space. Spaceflight can occur with spacecraft which may, or may not, have humans on board. Examples of human spaceflight include the Russian Soyuz program, the U.S. Space shuttle program, as well as the ongoing International Space Station...

to begin.
Length
In geometric measurements, length most commonly refers to the longest dimension of an object.In certain contexts, the term "length" is reserved for a certain dimension of an object along which the length is measured. For example it is possible to cut a length of a wire which is shorter than wire...

s between 100 and 1,000 kilometre
Kilometre
The kilometre is a unit of length in the metric system, equal to one thousand metres and is therefore exactly equal to the distance travelled by light in free space in of a second...

s (105 and 106 metre
Metre
The metre , symbol m, is the base unit of length in the International System of Units . Originally intended to be one ten-millionth of the distance from the Earth's equator to the North Pole , its definition has been periodically refined to reflect growing knowledge of metrology...

s).

## Conversions

A distance of 100 kilometres is equal to about 62 miles
(or 100 kilometres (62.13727366 mi)).

## Human-defined scales and structures

• 108 km — length of High Speed 1 between London and the Channel Tunnel
• 111 km — distance covered by one degree of latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...

on Earth's surface
• 130 km — range of a Scud-A
Scud
Scud is a series of tactical ballistic missiles developed by the Soviet Union during the Cold War, and exported widely to other countries. The term comes from the NATO reporting name SS-1 Scud which was attached to the missile by Western intelligence agencies...

missile
• 163 km — length of the Suez Canal
Suez Canal
The Suez Canal , also known by the nickname "The Highway to India", is an artificial sea-level waterway in Egypt, connecting the Mediterranean Sea and the Red Sea. Opened in November 1869 after 10 years of construction work, it allows water transportation between Europe and Asia without navigation...

• 180 km — distance between Mumbai
Mumbai
Mumbai , formerly known as Bombay in English, is the capital of the Indian state of Maharashtra. It is the most populous city in India, and the fourth most populous city in the world, with a total metropolitan area population of approximately 20.5 million...

and Nashik
• 213 km — length of Paris Métro
Paris Métro
The Paris Métro or Métropolitain is the rapid transit metro system in Paris, France. It has become a symbol of the city, noted for its density within the city limits and its uniform architecture influenced by Art Nouveau. The network's sixteen lines are mostly underground and run to 214 km ...

• 217 km — length of the Grand Union Canal
Grand Union Canal
The Grand Union Canal in England is part of the British canal system. Its main line connects London and Birmingham, stretching for 137 miles with 166 locks...

• 220 km — distance between Pune
Pune
Pune , is the eighth largest metropolis in India, the second largest in the state of Maharashtra after Mumbai, and the largest city in the Western Ghats. Once the centre of power of the Maratha Empire, it is situated 560 metres above sea level on the Deccan plateau at the confluence of the Mula ...

and Nashik
• 223 km — length of the Madrid Metro
The Madrid Metro is a metro system serving the city of Madrid, capital of Spain. The system is the sixth longest metro in the world though Madrid is approximately the fiftieth most populous metropolitan area in the world...

• 300 km — range of a Scud-B
Scud
Scud is a series of tactical ballistic missiles developed by the Soviet Union during the Cold War, and exported widely to other countries. The term comes from the NATO reporting name SS-1 Scud which was attached to the missile by Western intelligence agencies...

missile
• 300 km — the approximate distance travelled by light in one millisecond
Millisecond
A millisecond is a thousandth of a second.10 milliseconds are called a centisecond....

• 386 km — altitude of the International Space Station
International Space Station
The International Space Station is a habitable, artificial satellite in low Earth orbit. The ISS follows the Salyut, Almaz, Cosmos, Skylab, and Mir space stations, as the 11th space station launched, not including the Genesis I and II prototypes...

• 408 km — length of the London Underground
London Underground
The London Underground is a rapid transit system serving a large part of Greater London and some parts of Buckinghamshire, Hertfordshire and Essex in England...

(active track)
• 470 km — distance from Dublin to London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

as the crow flies
As the crow flies
"As the crow flies" or beelining is an idiom for the shortest route between two points; the geodesic distance.An example is the great-circle distance between Key West and Pensacola, at either end of the U.S...

• 500 km — widest width of Sweden
Geography of Sweden
Sweden is a country in Northern Europe on the Scandinavian Peninsula. Its borders are Norway to the west; Finland to the northeast; and the Baltic Sea and Gulf of Bothnia to the east and south....

from east to west
• 550 km — distance from San Francisco to Los Angeles
Los Angeles, California
Los Angeles , with a population at the 2010 United States Census of 3,792,621, is the most populous city in California, USA and the second most populous in the United States, after New York City. It has an area of , and is located in Southern California...

as the crow flies
As the crow flies
"As the crow flies" or beelining is an idiom for the shortest route between two points; the geodesic distance.An example is the great-circle distance between Key West and Pensacola, at either end of the U.S...

• 560 km — distance of Bordeaux–Paris, formerly the longest one-day professional cycling race
• 590 km — length of land boundary between Finland
Geography of Finland
The geography of Finland differs from that of other Nordic countries. Bordering the Baltic Sea, Gulf of Bothnia, and Gulf of Finland, as well as Sweden, Norway, and Russia, Finland is the northernmost country on the European continent...

and Sweden
Geography of Sweden
Sweden is a country in Northern Europe on the Scandinavian Peninsula. Its borders are Norway to the west; Finland to the northeast; and the Baltic Sea and Gulf of Bothnia to the east and south....

• 600 km — range of a Scud
Scud
Scud is a series of tactical ballistic missiles developed by the Soviet Union during the Cold War, and exported widely to other countries. The term comes from the NATO reporting name SS-1 Scud which was attached to the missile by Western intelligence agencies...

-C missile
• 600 km — height above ground of the Hubble Space Telescope
Hubble Space Telescope
The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...

• 804.67 km — (500 miles) distance of the Indy 500 automobile race
• 871 km — distance from Sydney
Sydney
Sydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...

to Melbourne
Melbourne
Melbourne is the capital and most populous city in the state of Victoria, and the second most populous city in Australia. The Melbourne City Centre is the hub of the greater metropolitan area and the Census statistical division—of which "Melbourne" is the common name. As of June 2009, the greater...

(along the Hume Highway
Hume Highway
The Hume Highway/Hume Freeway is one of Australia's major inter-city highways, running for 880 km between Sydney and Melbourne. It is part of the Auslink National Network and is a vital link for road freight to transport goods to and from the two cities as well as serving Albury-Wodonga and...

)

## Nature

• 203 km — length of Sognefjorden, the second largest fjord in the world
• 240 km — widest width of the English Channel
English Channel
The English Channel , often referred to simply as the Channel, is an arm of the Atlantic Ocean that separates southern England from northern France, and joins the North Sea to the Atlantic. It is about long and varies in width from at its widest to in the Strait of Dover...

• 430 km — length of the Pyrenees
Pyrenees
The Pyrenees is a range of mountains in southwest Europe that forms a natural border between France and Spain...

• 724 km — length of the Om River
Om River
Om is a river in the south of Western Siberian plains in Russia. It is ~724 km long, flowing into the major Irtysh River. It rises in the Vasyugan Swamp at the border of Novosibirsk and Omsk oblasts....

• 897 km — length of the River Douro

## Astronomical

• 100 km — the altitude at which the FAI
Fédération Aéronautique Internationale
The Fédération Aéronautique Internationale is the world governing body for air sports and aeronautics and astronautics world records. Its head office is in Lausanne, Switzerland. This includes man-carrying aerospace vehicles from balloons to spacecraft, and unmanned aerial vehicles...

defines spaceflight
Spaceflight
Spaceflight is the act of travelling into or through outer space. Spaceflight can occur with spacecraft which may, or may not, have humans on board. Examples of human spaceflight include the Russian Soyuz program, the U.S. Space shuttle program, as well as the ongoing International Space Station...

to begin
• 167 km — diameter of Amalthea
Amalthea (moon)
Amalthea is the third moon of Jupiter in order of distance from the planet. It was discovered on September 9, 1892, by Edward Emerson Barnard and named after Amalthea, a nymph in Greek mythology. It is also known as '....

, one of Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...

's inner moons
• 220 km — diameter of Phoebe
Phoebe (moon)
Phoebe is an irregular satellite of Saturn. It was discovered by William Henry Pickering on 17 March 1899 from photographic plates that had been taken starting on 16 August 1898 at the Boyden Observatory near Arequipa, Peru, by DeLisle Stewart...

, the largest of Saturn
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...

's outer moons
• 340 km — diameter of Nereid
Nereid (moon)
Nereid , also known as Neptune II, is the third-largest moon of Neptune. It has a highly eccentric orbit. Nereid was discovered by Gerard Kuiper in 1949 and was the second moon of Neptune to be discovered.- Discovery and naming :...

, the third largest moon of Neptune
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...

• 350 km — lower bound of Low Earth orbit
Low Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...

• 420 km — diameter of Proteus
Proteus (moon)
Proteus , also known as Neptune VIII, is the second largest Neptunian moon, and Neptune's largest inner satellite. Discovered by Voyager 2 spacecraft in 1989, it is named after Proteus, the shape-changing sea god of Greek mythology...

, the second largest moon of Neptune
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...

• 468 km — diameter of the asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...

4 Vesta
4 Vesta
Vesta, formally designated 4 Vesta, is one of the largest asteroids, with a mean diameter of about . It was discovered by Heinrich Wilhelm Olbers on March 29, 1807, and is named after the Roman virgin goddess of home and hearth, Vesta....

• 472 km — diameter of Miranda
Miranda (moon)
-External links:* at * at The Nine8 Planets* at Views of the Solar System* * from the...

, one of Uranus
Uranus
Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus , the father of Cronus and grandfather of Zeus...

' major moons
• 974.6 km — greatest diameter of 1 Ceres, the largest solar system asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...