Orders of magnitude (length)

The following are examples of orders of magnitude for different lengths.

Orders of magnitude (english annotations)
Objects of sizes in different order of magnitude.

Overview

Scale Range (m) Unit Example items
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Subatomic 0 singularity
10−35 P Fixed value (not a range). Quantum foam, string
10−18 am Electron, quark
Atomic to cellular 10−15 10−12 fm Atomic nucleus, proton, neutron
10−12 10−9 pm Wavelength of gamma rays and X-rays, hydrogen atom
10−9 10−6 nm DNA helix, virus, wavelength of optical spectrum
Cellular to human 10−6 10−3 μm Bacterium, fog water droplet, human hair's diameter[note 1]
10−3 1 mm Mosquito, golf ball, domestic cat, violin, football
Human to astronomical 100 103 m Piano, human, automobile, sperm whale, football field, Eiffel Tower
103 106 km Mount Everest, length of Panama Canal and Trans-Siberian Railway, larger asteroid
Astronomical 106 109 Mm The Moon, Earth, one light-second
109 1012 Gm Sun, one light-minute, Earth's orbit
1012 1015 Tm Orbits of outer planets, Solar System
1015 1018 Pm A light-year, the distance to Proxima Centauri
1018 1021 Em Galactic arm
1021 1024 Zm Milky Way, distance to Andromeda Galaxy
1024 Ym Huge-LQG, Hercules–Corona Borealis Great Wall, visible universe

Detailed list

To help compare different orders of magnitude, the following list describes various lengths between  metres and metres.

Subatomic scale

Factor (m) Multiple Value Item
0 0 0 singularity
10−35 1 Planck length 0.0000000000162 ym  Planck length; typical scale of hypothetical loop quantum gravity or size of a hypothetical string and of branes; according to string theory lengths smaller than this do not make any physical sense.[1] Quantum foam is thought to exist at this level.
10−24 1 yoctometre (ym) 2 ym Effective cross section radius of 1 MeV neutrinos[2]
10−21 1 zeptometre (zm) Preons, hypothetical particles proposed as subcomponents of quarks and leptons; the upper bound for the width of a cosmic string in string theory
7 zm Effective cross section radius of high-energy neutrinos[3]
310 zm De Broglie wavelength of protons at the Large Hadron Collider (4 TeV as of 2012)
10−18 1 attometre (am) Upper limit for the size of quarks and electrons
Sensitivity of the LIGO detector for gravitational waves[4]
Upper bound of the typical size range for "fundamental strings"[1]
10−17 10 am Range of the weak force
10−16 100 am 850 am Approximate proton radius[5]

Atomic to cellular scale

Factor (m) Multiple Value Item
10−15 1 femtometre (fm) 1.5 fm Size of an 11 MeV proton[6]
2.81794 fm Classical electron radius[7]
1.75 to 15 fm Diameter range of the atomic nucleus[1][8]
10−12 1 picometre (pm) 0.75 to 0.8225 pm Longest wavelength of gamma rays
1 pm Distance between atomic nuclei in a white dwarf
2.4 pm Compton wavelength of electron
5 pm Wavelength of shortest X-rays
10−11 10 pm
31 pm Radius of helium atom
53 pm Bohr radius (radius of a hydrogen atom)
10−10 100 pm 100 pm 1 ångström (also covalent radius of sulfur atom[9])
154 pm Length of a typical covalent bond (C–C)
280 pm Average size of the water molecule; actual lengths may vary.
500 pm Width of protein α helix
10−9 1 nanometre (nm) 1 nm Diameter of a carbon nanotube[10]
2 nm Diameter of the DNA helix[11]
2.5 nm Smallest microprocessor transistor gate oxide thickness (as of January 2007)
3.4 nm Length of a DNA turn (10 bp)[12]
6–10 nm Thickness of cell membrane
10−8 10 nm 10 nm Thickness of cell wall in Gram-negative bacteria
10 nm As of 2016, the 10 nanometre was the smallest semiconductor device fabrication node[13]
40 nm Extreme ultraviolet wavelength
50 nm Flying height of the head of a hard disk[14]
10−7 100 nm 121.6 nm Wavelength of the Lyman-alpha line[15]
120 nm Typical diameter of the human immunodeficiency virus (HIV)[16]
400–700 nm Approximate wavelength range of visible light[17]

Cellular to human scale

Factor (m) Multiple Value Item
10−6 1 micrometre (μm)

(also called 1 micron)

1–4 μm Typical length of a bacterium[18]
4 μm Typical diameter of spider silk[19]
7 μm Typical size of a red blood cell[20]
10−5 10 μm 10 μm Typical size of a fog, mist, or cloud water droplet
10 μm Width of transistors in the Intel 4004, the world's first commercial microprocessor
12 μm Width of acrylic fiber
17-181 μm Width range of human hair[21]
10−4 100 μm 340 μm Size of a single pixel on a 17-inch monitor with a resolution of 1024×768
560 μm Thickness of the central area of a human cornea[22]
750 μm Maximum diameter of Thiomargarita namibiensis, the largest bacterium ever discovered (as of 2010)
10−3 1 millimetre (mm) 1.5 mm Length of an average flea[23]
2.54 mm 1/10th inch; distance between pins in DIP (dual-inline-package) electronic components
5.70 mm Diameter of the projectile in 5.56×45mm NATO ammunition
10−2 1 centimetre (cm) 20 mm Approximate width of an adult human finger
54 mm x 86 mm Dimensions of a credit card, according to the ISO/IEC 7810 ID-1 standard
73–75 mm Diameter of a baseball, according to Major League Baseball guidelines[24]
10−1 1 decimetre (dm) 120 mm Diameter of a compact disk
660 mm Length of the longest pine cones, produced by the sugar pine[25]
900 mm Average length of a rapier, a fencing sword[26]

Human to astronomical scale

Factor (m) Multiple Value Item
1 metre 1 metre (m) 1 m (exactly) Since 1983, defined as length of the path travelled by light in vacuum
during a time interval of 1/299 792 458 of a second. See History of the metre for previous definitions.
2.72 m Height of Robert Wadlow, tallest known human being.[27]
8.38 m Length of a London bus (AEC Routemaster)
101 1 decametre (dam) 33 m Length of the longest known blue whale[28]
52 m Height of the Niagara Falls.[29]
93.47 m Height of the Statue of Liberty
102 1 hectometre (hm) 105 m Length of a typical football field
137 m (147 m) Height (present and original) of the Great Pyramid of Giza
300 m Height of the Eiffel Tower, one of the famous monuments of Paris
979 m Height of the Salto Angel, the world's highest free-falling waterfall (Venezuela)
103 1 kilometre (km) 2.3 km Axial length of the Three Gorges Dam, the largest dam in the world[30]
3.1 km Narrowest width of the Strait of Messina, separating Italy and Sicily
8.848 km Height of Mount Everest, the highest mountain on Earth
104 10 km 10.9 km Depth of the Challenger Deep in the Mariana Trench, the deepest known point on Earth's surface
27 km Circumference of the Large Hadron Collider, as of May 2010 the largest and highest energy particle accelerator
42.195 km Length of a marathon
105 100 km
100 km The distance the IAU considers to be the limit to space, called the Karman line
163 km Length of the Suez Canal, connecting the Mediterranean Sea to the Red Sea
491 km Length of the Pyrenees, the mountain range separating Spain and France
974.6 km Greatest diameter of the dwarf planet Ceres.[31]

Astronomical scale

Factor (m) Multiple Value Item
106 1 megametre (Mm) 2.38 Mm Diameter of dwarf planet Pluto, formerly the smallest planet category[note 2] in the Solar System
3.48 Mm Diameter of the Moon
5.2 Mm Typical distance covered by the winner of the 24 Hours of Le Mans automobile endurance race
6.4 Mm Length of the Great Wall of China
6.6 Mm Approximate length of the two longest rivers, the Nile and the Amazon
7.821 Mm Length of the Trans-Canada Highway
9.288 Mm Length of the Trans-Siberian Railway, longest in the world
107 10 Mm 12.756 Mm Equatorial diameter of Earth
40.075 Mm Length of Earth's equator
108 100 Mm 142.984 Mm Diameter of Jupiter
299.792 Mm Distance traveled by light in one second
384.4 Mm Moon's orbital distance from Earth
109 1 gigametre (Gm) 1.39 Gm Diameter of the Sun
4.8 Gm Greatest mileage ever recorded by a car (3 million miles by a 1966 Volvo P-1800S, still driving)
1010 10 Gm 18 Gm Approximately one light-minute
1011 100 Gm 150 Gm 1 astronomical unit (AU); mean distance between Earth and Sun
1012 1 terametre (Tm) 1.3 Tm Optical diameter of Betelgeuse
1.4 Tm Orbital distance of Saturn from Sun
2 Tm Estimated optical diameter of VY Canis Majoris, one of the largest known stars
5.9 Tm Orbital distance of Pluto from Sun
~ 7.5 Tm Outer boundary of the Kuiper belt, inner boundary of the Oort cloud (~ 50 AU)
1013 10 Tm Diameter of the Solar System as a whole[1]
21.49 Tm Distance of the Voyager 1 spacecraft from Sun (as of Oct 2018), the farthest man-made object so far[32]
62.03 Tm Estimated radius of the event horizon of the supermassive black hole in NGC 4889, the largest known black hole to date
1014 100 Tm 180 Tm Size of the debris disk around the star 51 Pegasi[33]
200 Tm Total length of DNA molecules in all cells of an adult human body
1015 1 petametre (Pm) ~7.5 Pm Supposed outer boundary of the Oort cloud (~ 50,000 AU)
9.461 Pm Distance traveled by light in one year; at its current speed, Voyager 1 would need 17,500 years to travel this distance
1016 10 Pm 30.857 Pm 1 parsec
39.9 Pm Distance to nearest star (Proxima Centauri)
41.3 Pm As of March 2013, distance to nearest discovered extrasolar planet (Alpha Centauri Bc)
1017 100 Pm 193 Pm As of October 2010, distance to nearest discovered extrasolar planet with potential to support life as we know it (Gliese 581 d)
615 Pm Approximate radius of humanity's radio bubble, caused by high-power TV broadcasts leaking through the atmosphere into outer space
1018 1 exametre (Em) 1.9 Em Distance to nearby solar twin (HIP 56948), a star with properties virtually identical to our Sun[34]
1019 10 Em 9.46 Em Average thickness of Milky Way Galaxy[35] (1000 to 3000 ly by 21 cm observations[36])
1020 100 Em 113.5 Em Thickness of Milky Way Galaxy's gaseous disk[37]
1021 1 zettametre (Zm)
1.54 Zm Distance to SN 1987A, the most recent naked eye supernova
1.62 Zm Distance to the Large Magellanic Cloud (a dwarf galaxy orbiting the Milky Way)
1.66 Zm Distance to the Small Magellanic Cloud (another dwarf galaxy orbiting the Milky Way)
1.9 Zm Diameter of galactic disk of Milky Way Galaxy[38][39][40][41]
6.15 Zm Diameter of the low surface brightness disc halo of the giant spiral galaxy Malin 1
1022 10 Zm 13.25 Zm Radius of the diffuse stellar halo of IC 1101, one of the largest known galaxies
24 Zm Distance to Andromeda Galaxy
30.857 Zm 1 megaparsec
50 Zm Diameter of Local Group of galaxies
1023 100 Zm 300–600 Zm Distance to Virgo cluster of galaxies
1024 1 yottametre (Ym) 2.19 Ym Diameter of the Local Supercluster and the largest voids and filaments
2.8 Ym End of Greatness
~5 Ym Diameter of the Horologium Supercluster[42]
9.461 Ym Diameter of the Pisces–Cetus Supercluster Complex, the supercluster complex where we live
1025 10 Ym 13 Ym Length of the Sloan Great Wall, a giant wall of galaxies (galactic filament)[43]
30.857 Ym 1 gigaparsec
37.84 Ym Length of the Huge-LQG, a group of 73 quasars
1026 100 Ym 95 Ym Estimated light travel distance to certain quasars. Length of the Hercules–Corona Borealis Great Wall, a colossal wall of galaxies, the largest and the most massive structure in the observable universe as of 2014
127 Ym Estimated light travel distance to UDFj-39546284, the most distant object ever observed
870 Ym Approximate diameter (comoving distance) of the visible universe[1]
1027 1000 Ym 1200 Ym Lower bound of the (possibly infinite) radius of the universe, if it is a 3-sphere, according to one estimate using the WMAP data at 95% confidence[44] It equivalently implies that there are at minimum 21 particle horizon-sized volumes in the universe.
[note 3] Ym Ym According to the laws of probability, the distance one must travel until one encounters a volume of space identical to our observable universe with conditions identical to our own.[45][46]
Ym Ym Maximum size of universe after cosmological inflation, implied by one resolution of the No-Boundary Proposal[47]

less than 10 yoctometres

To help compare different orders of magnitude, this section lists lengths shorter than 10−23 m (10 ym).

  • 0 – singularity
  • 1.6 × 10−11 yoctometres (1.6 × 10−35 metres) – the Planck length (Measures of distance shorter than this are considered nonsensical and do not make any physical sense, according to current theories of physics).
  • 1 ym – 1 yoctometre, the smallest named subdivision of the metre in the SI base unit of length, one septillionth of a metre
  • 1 ym – length of a neutrino.
  • 2 ym – the effective cross-section radius of 1 MeV neutrinos as measured by Clyde Cowan and Frederick Reines

10 yoctometres

To help compare different orders of magnitude, this section lists lengths between 10−23 metres and 10−22 metres (10 ym and 100 ym).

100 yoctometres

To help compare different orders of magnitude, this section lists lengths between 10−22 m and 10−21 m (100 ym and 1 zm).

  • 100 ym – length of a top quark, one of the smallest known quarks

1 zeptometre

To help compare different orders of magnitude, this section lists lengths between 10−21 m and 10−20 m (1 zm and 10 zm).

  • 2 zm – length of a preon, hypothetical particles proposed as subcomponents of quarks and leptons; the upper bound for the width of a cosmic string in string theory.
  • 2 zm – radius of effective cross section for a 20 GeV neutrino scattering off a nucleon
  • 7 zm – radius of effective cross section for a 250 GeV neutrino scattering off a nucleon

10 zeptometres

To help compare different orders of magnitude, this section lists lengths between 10−20 m and 10−19 m (10 zm and 100 zm).

  • 15 zm – length of a high energy neutrino
  • 30 zm – length of a bottom quark

100 zeptometres

To help compare different orders of magnitude, this section lists lengths between 10−19 m and 10−18 m (100 zm and 1 am).

1 attometre

To help compare different orders of magnitude, this section lists lengths between 10−18 m and 10−17 m (1 am and 10 am).

10 attometres

To help compare different orders of magnitude, this section lists lengths between 10−17 m and 10−16 m (10 am and 100 am).

  • 10 am – range of the weak force

100 attometres

To help compare different orders of magnitude, this section lists lengths between 10−16 m and 10−15 m (100 am and 1 fm).

  • 100 am – all lengths shorter than this distance are not confirmed in terms of size
  • 850 am – approximate proton radius

1 femtometre

The femtometre (symbol fm) is a unit of length in the metric system, equal to 10−15 metres. In particle physics, this unit is more commonly called a fermi, also with abbreviation "fm". To help compare different orders of magnitude, this section lists lengths between 10−15 metres and 10−14 metres (1 femtometre and 10 fm).

10 femtometres

To help compare different orders of magnitude, this section lists lengths between 10−14 m and 10−13 m (10 fm and 100 fm).

100 femtometres

To help compare different orders of magnitude, this section lists lengths between 10−13 m and 10−12 m (100 fm and 1 pm).

  • 570 fm – typical distance from the atomic nucleus of the two innermost electrons (electrons in the 1s shell) in the uranium atom, the heaviest naturally-occurring atom

1 picometre

To help compare different orders of magnitude this section lists lengths between 10−12 and 10−11 m (1 pm and 10 pm).

10 picometres

To help compare different orders of magnitude this section lists lengths between 10−11 and 10−10 m (10 pm and 100 pm).

100 picometres

To help compare different orders of magnitude this section lists lengths between 10−10 and 10−9 m (100 pm and 1 nm).

1 nanometre

To help compare different orders of magnitude this section lists lengths between 10−9 and 10−8 m (1 nm and 10 nm).

10 nanometres

To help compare different orders of magnitude this section lists lengths between 10−8 and 10−7 m (10 nm and 100 nm).

100 nanometres

Comparison semiconductor process nodes
Comparison of sizes of semiconductor manufacturing process nodes with some microscopic objects and visible light wavelengths. At this scale, the width of a human hair is about 10 times that of the image.[55]

To help compare different orders of magnitude, this section lists lengths between 10−7 and 10−6 m (100 nm and 1 μm).

1 micrometre

Loxoceles reclusa iconized thread
The silk for a spider's web is around 5–7μm wide.

To help compare different orders of magnitude, this section lists some items with lengths between 10−6 and 10−5 m (between 1 and 10 micrometres, or μm).

10 micrometres

FogParticlesHighSpeed
Fog particles are around 10–50 μm long.

To help compare different orders of magnitude, this section lists lengths between 10−5 m and 10−4 m (10 μm and 100 μm).

  • 10 μm – width of cotton fibre[66]
  • 10 μm – transistor width of the Intel 4004, the world's first commercial microprocessor
  • 10 μm – mean longest dimension of a human red blood cell
  • 5–20 μm – dust mite excreta[67]
  • 10.6 μm – wavelength of light emitted by a carbon dioxide laser
  • 15 μm – width of silk fibre
  • 17 μm – minimum width of a strand of human hair[21]
  • 17.6 μm – one twip, a unit of length in typography
  • 10 to 55 μm – width of wool fibre[66]
  • 25.4 μm – 1/1000 inch, commonly referred to as 1 mil in the U.S. and 1 thou in the UK
  • 30 μm – length of a human skin cell
  • 50 μm – typical length of Euglena gracilis, a flagellate protist
  • 50 μm – typical length of a human liver cell, an average-sized body cell
  • 50 μm – length of a silt particle
  • 60 μm – length of a sperm cell
  • 70 to 180 μm – thickness of paper

100 micrometres

Paramecium
A paramecium is around 300 μm long.

To help compare different orders of magnitude, this section lists lengths between 10−4 m and 10−3 m (100 μm and 1 mm). The term myriometre (abbr. mom, equivalent to 100 micrometres; frequently confused with the myriametre, 10 kilometres)[68] is deprecated; the decimal metric prefix myrio-[69] is obsolete[70][71][72] and was not included among the prefixes when the International System of Units was introduced in 1960.

  • 100 μm – 1/10 of a millimetre
  • 100 μm – 0.00394 inches
  • 100 μm – smallest distance that can be seen with the naked eye
  • 100 μm – average diameter of a strand of human hair[21]
  • 100 μm – thickness of a coat of paint
  • 100 μm – length of a dust particle
  • 120 μm – the geometric mean of the Planck length and the diameter of the observable universe: 8.8 × 1026 m × 1.6 × 10−35 m
  • 120 μm – diameter of a human ovum
  • 170 μm – length of the largest sperm cell in nature, belonging to the Drosophila bifurca fruit fly[73][74]
  • 181 μm – maximum width of a strand of human hair[21]
  • 100–400 μm – length of Demodex mites living in human hair follicles
  • 200 μm – typical length of Paramecium caudatum, a ciliate protist
  • 200 μm - nominal width of the smallest commonly available mechanical pencil lead (0.2 mm)
  • 250–300 μm – length of a dust mite[75]
  • 340 μm – length of a single pixel on a 17-inch monitor with a resolution of 1024×768
  • 500 μm – typical length of Amoeba proteus, an amoeboid protist
  • 500 μm – MEMS micro-engine
  • 500 μm – average length of a grain of sand
  • 500 μm – average length of a grain of salt
  • 500 μm – average length of a grain of sugar
  • 560 μm – thickness of the central area of a human cornea[22]
  • 750 μm – diameter of a Thiomargarita namibiensis, the largest bacteria known[76]
  • 760 μm – thickness of an identification card

1 millimetre

Fire ants 01
An average red ant is about 5 mm long.

To help compare different orders of magnitude, this section lists lengths between 10−3 m and 10−2 m (1 mm and 1 cm).

1 centimetre

Fingernail label (enwiki)
An average human fingernail is about 1 cm wide.

To help compare different orders of magnitude, this section lists lengths between 10−2 m and 10−1 m (1 cm and 1 dm).

1 decimetre

Foot on white background
An adult human foot is about 28 centimetres long.

To help compare different orders of magnitude, this section lists lengths between 10 centimetres and 100 centimetres (10−1 metre and 1 metre).

Conversions

10 centimetres (abbreviated to 10 cm) is equal to:

Wavelengths

Human-defined scales and structures

  • 10.16 cm = 1.016 dm – 1 hand used in measuring height of horses (4 inches)
  • 12 cm = 1.2 dm – diameter of a compact disc (CD) (= 120 mm)
  • 15 cm = 1.5 dm – length of a Bic pen with cap on
  • 22 cm = 2.2 dm – diameter of a typical association football (soccer ball)
  • 30 cm = 3 dm – typical school-use ruler length (= 300 mm)
  • 30.48 cm = 3.048 dm – 1 foot (measure)
  • 60 cm = 6 dm – standard depth (front to back) of a domestic kitchen worktop in Europe (= 600 mm)
  • 90 cm = 9 dm – average length of a rapier, a fencing sword[26]
  • 91.44 cm = 9.144 dm – one yard (measure)

Nature

  • 10 cm = 1 dm – diameter of the human cervix upon entering the second stage of labour
  • 11 cm = 1.1 dm – diameter of an average potato
  • 15 cm = 1.5 dm – approximate size of largest beetle species
  • 19 cm = 1.9 dm – length of a banana
  • 26.3 cm = 2.6 dm – length of average male human foot
  • 29.98 cm = 2.998 dm – distance light travels in one nanosecond
  • 31 cm = 3.1 dm – wingspan of largest butterfly species Ornithoptera alexandrae
  • 46 cm = 4.6 dm – length of an average domestic cat
  • 50 to 65 cm = 5–6.5 dm – a coati's tail
  • 66 cm = 6.6 dm – length of the longest pine cones (produced by the sugar pine[84])

Astronomical

  • 84 cm = 8.4 dm – approximate diameter of 2008 TS26, a meteoroid

1 metre

Da Vinci Vitruve Luc Viatour
Leonardo da Vinci drew the Vitruvian Man within a square of side 1.83 metres and a circle about 1.2 metres in radius

To help compare different orders of magnitude, this section lists lengths between one metre and ten metres. Light travels 1 metre in ​1299,792,458, or 3.3356409519815E-9 of a second.

Conversions

1 metre is:

Human-defined scales and structures

  • 1 m – approximate height of the top part of a doorknob on a door
  • 1 m – diameter of a very large beach ball
  • 1.435 m – standard gauge of railway track used by about 60% of railways in the world = 4' 8½"
  • 2.5 m – distance from the floor to the celling in an average residential house[85]
  • 2.7 m – length of the Starr Bumble Bee II, the smallest plane
  • 2.77–3.44 m – wavelength of the broadcast radio FM band 87–108 MHz
  • 3.05 m – the length of an old Mini
  • 8.38 m – the length of a London Bus (AEC Routemaster)

Sports

Nature

  • 1 m – height of Homo floresiensis (the "Hobbit")
  • 1.15 m – a pizote (mammal)
  • 1.37 m – average height of an Andamanese person
  • 1.63 m – (5 feet 4 inches) (or 64 inches) - height of average US female human as of 2002 (source: US Centers for Disease Control and Prevention (CDC))
  • 1.75 m – (5 feet 8 inches) - height of average US male human as of 2002 (source: US CDC as per female above)
  • 2.5 m – height of a sunflower
  • 2.72 m – (8 feet 11 inches) - tallest known human being (Robert Wadlow)[27]
  • 3.63 m – the record wingspan for living birds (a wandering albatross)
  • 5 m – length of an elephant
  • 5.20 m – height of a giraffe[89]
  • 5.5 m – height of a Baluchitherium, the largest land mammal ever lived
  • 7 m – wingspan of Argentavis, the largest flying bird known
  • 7.50 m – approximate length of the human gastrointestinal tract

Astronomical

1 decametre

Image-Blue Whale and Hector Dolphine Colored
A blue whale has been measured as 33 metres long; this drawing compares its length to that of a human diver and a dolphin

To help compare different orders of magnitude, this section lists lengths between 10 metres and 100 metres.

Conversions

10 metres (very rarely termed a decametre which is abbreviated as dam) is equal to:

Human-defined scales and structures

Sports

  • 11 metres – approximate width of a doubles tennis court
  • 15 metres – width of a standard FIBA basketball court
  • 15.24 metres – width of an NBA basketball court (50 feet)
  • 18.44 metres – distance between the front of the pitcher's rubber and the rear point of home plate on a baseball field (60 feet, 6 inches)[91]
  • 20 metres – length of cricket pitch (22 yards)[92]
  • 27.43 metres – distance between bases on a baseball field (90 feet)
  • 28 metres – length of a standard FIBA basketball court
  • 28.65 metres – length of an NBA basketball court (94 feet)
  • 49 metres – width of an American football field (53⅓ yards)
  • 59.436 metres – width of a Canadian football field (65 yards)
  • 70 metres – typical width of soccer field
  • 91 metres – length of American football field (100 yards, measured between the goal lines)
  • 105 metres – length of football pitch (UEFA Stadium Category 3 and 4)

Nature

Astronomical

1 hectometre

Cheops pyramid 01
The Great Pyramid of Giza is 138.8 metres high.
M27 DLS
British driver location sign and location marker post on the M27 in Hampshire. The location marker posts are installed at 100-metre intervals[94]

To compare different orders of magnitude this section lists lengths between 100 metres and 1000 metres (1 kilometre).

Conversions

100 metres (sometimes termed a hectometre) is equal to:

  • 328 feet
  • one side of a 1 hectare square
  • a fifth of a modern li, a Chinese unit of measurement
  • the approximate distance travelled by light in 300 nanoseconds

Human-defined scales and structures

Sports

Nature

Astronomical

1 kilometre

FujiSunriseKawaguchiko2025WP
Mount Fuji is 3.776 kilometres (3,776 metres) high

To help compare different orders of magnitude, this section lists lengths between 1 kilometre and 10 kilometres (103 and 104 metres).

Conversions

1 kilometre (unit symbol km) is equal to:

Human-defined scales and structures

Geographical

Astronomical

10 kilometres

Strait of Gibraltar 5.53940W 35.97279N
The Strait of Gibraltar is 13 kilometres wide

To help compare different orders of magnitude, this section lists lengths between 10 and 100 kilometres (104 to 105 metres). The myriametre[111] (sometimes also spelled myriameter, myriometre and myriometer) (10,000 metres) is a deprecated unit name; the decimal metric prefix myria-[69] (sometimes also written as myrio-[112][113][114]) is obsolete[70][71][72] and not included among the prefixes when the International System of Units was introduced in 1960.

Conversions

10 kilometres is equal to:

Myriameterstein36RüdesheimRhein
Distance marker on the Rhine: 36 (XXXVI) myriametres from Basel. The stated distance is 360 km; comma is the decimal separator in Germany.

Sports

Human-defined scales and structures

Geographical

Astronomical

100 kilometres

Suez canal 30.55N 32.28E
The Suez Canal is 163 kilometres long

A length of 100 kilometres (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 to begin.

To help compare orders of magnitude, this section lists lengths between 100 and 1,000 kilometres (105 and 106 metres).

Conversions

A distance of 100 kilometres is equal to about 62 miles (or 62.13711922 miles).

Human-defined scales and structures

Geographical

Astronomical

1 megametre

1e6m comparison Mars Mercury Moon Pluto Haumea - no transparency
Small planets, the Moon and dwarf planets in our solar system have diameters from one to ten million metres. Top row: Mars (left), Mercury (right); bottom row: Moon (left), Pluto (center), and Haumea (right), to scale.

To help compare different orders of magnitude, this section lists lengths starting at 106 m (1 Mm or 1,000 km).

Conversions

1 megametre is equal to:

Human-defined scales and structures

Sports

Geographical

Astronomical

10 megametres

1e7m comparison Uranus Neptune Sirius B Earth Venus
Planets from Venus up to Uranus have diameters from ten to one hundred million metres. Top row: Uranus (left), Neptune (right); middle row: Earth (left), Sirius B (center), and Venus (right), to scale

To help compare different orders of magnitude, this section lists lengths starting at 107 metres (10 megametres or 10,000 kilometres).

Conversions

10 megametres (10 Mm) is

Human-defined scales and structures

Geographical

Astronomical

100 megametres

1e8m comparison Saturn Jupiter OGLE-TR-122b with Uranus Neptune Sirius B Earth Venus no transparency
The Earth-Moon orbit, Saturn, OGLE-TR-122b, Jupiter, and other objects, to scale. Click on image for detailed view and links to other length scales.

To help compare different orders of magnitude, this section lists lengths starting at 108 metres (100 megametres or 100,000 kilometres or 62,150 miles).

1 gigametre

1e9m comparison
Upper part: Gamma Orionis, Algol B, the Sun (centre), underneath their darker mirror images (artist's interpretation), and other objects, to scale.

To help compare different distances this section lists lengths starting at 109 metres (1 gigametre (Gm) or 1 billion metres).

10 gigametres

1e10m comparison Rigel, Aldebaran, and smaller - antialiased no transparency
Rigel and Aldebaran (top left and right) compared to smaller stars, the Sun (very small dot in lower middle, with orbit of Mercury as yellow ellipse) and transparent sphere with radius of one light minute.

To help compare different distances this section lists lengths starting at 1010 metres (10 gigametres (Gm) or 10 million kilometres, or 0.07 Astronomical units).

100 gigametres

1e11m comparison R Doradus and Betelgeuse, and smaller - antialiased no transparency
From largest to smallest: Jupiter's orbit, red supergiant star Betelgeuse, Mars' orbit, Earth's orbit, star R Doradus, and orbits of Venus, Mercury. Inside R Doradus' depiction are the blue giant star Rigel and red giant star Aldebaran. The faint yellow glow around the Sun represents one light minute. Click image to see more details and links to their scales.

To help compare distances at different orders of magnitude this section lists lengths starting at 1011 metres (100 gigametre|Gm or 100 million kilometres or 0.7 astronomical units).

  • 109 Gm – 0.7 AU – Distance between Venus and the Sun
  • 149.6 Gm (93.0 million mi) – 1.0 AU – Distance between the Earth and the Sun - the definition of the astronomical unit
  • 180 Gm – 1.2 AU – Maximum diameter of Sagittarius A*, the supermassive black hole in the center of Milky Way galaxy
  • 228 Gm – 1.5 AU – Distance between Mars and the Sun
  • 570 Gm – 3.8 AU – Length of the tail of Comet Hyakutake measured by Ulysses; the actual value could be much higher
  • 591 Gm – 4.0 AU – Minimum distance between the Earth and Jupiter
  • 780 Gm – 5.2 AU – Distance between Jupiter and the Sun
  • 947 Gm – 6.4 AU – Diameter of Antares A
  • 965 Gm – 6.4 AU – Maximum distance between the Earth and Jupiter

1 terametre

Terameter group
8 things in the terameter group
1e12m comparison Kuiper belt and smaller
Comparison of size of the Kuiper belt (large faint torus) with the star VY Canis Majoris (within Saturn's orbit), Betelgeuse (inside Jupiter's orbit) and R Doradus (small central red sphere) together with the orbits of Neptune and Uranus, to scale. The yellow ellipses represent the orbits of each planet and the dwarf planet Pluto.

To help compare different distances, this section lists lengths starting at 1012 m (1 Tm or 1 billion km or 6.7 astronomical units).

  • 1.079 Tm – 7.2 AU – One light-hour
  • 1.4 Tm – 9.5 AU – Distance between Saturn and the Sun
  • 1.83 Tm – 12.2 AU – Diameter of HR 5171 A, the largest known yellow hypergiant star although the latest research suggests it is a red hypergiant with a diameter about 2.1 Tm (14 AU)[136][137]
  • 1.5 Tm - 10 AU - Estimated diameter of VV Cephei A, a red supergiant.[138]
  • 2 Tm – 13.2 AU – Estimated diameter of VY Canis Majoris, one of the largest known stars.[139]
  • 2.9 Tm – 19.4 AU – Distance between Uranus and the Sun
  • 4 Tm – 26.7 AU – Previous estimated diameter of VY Canis Majoris based on direct measurements of the radius at infrared wavelengths.[140] The size was revised in 2012 through improved measurement techniques. (see above)[139]
  • 4.4 Tm – 29.4 AU – Perihelion distance of Pluto
  • 4.5 Tm – 30.1 AU – Distance between Neptune and the Sun
  • 4.5 Tm – 30.1 AU – Inner radius of the Kuiper belt
  • 5.7 Tm – 38.1 AU – Perihelion distance of Eris
  • 7.3 Tm – 48.8 AU – Aphelion distance of Pluto
  • 7.5 Tm – 50.1 AU – Outer radius of the Kuiper Belt, inner boundary of the Oort Cloud

10 terametres

1e13m comparison Hale Bopp and smaller - HQ no transparency
Sedna's orbit (left) is longer than 100 Tm, but other lengths are between 10 and 100 Tm: Comet Hale-Bopp's orbit (lower, faint orange); one light-day (yellow spherical shell with yellow Vernal point arrow as radius); the heliosphere's termination shock (blue shell); and other arrows show positions of Voyager 1 (red) and Pioneer 10 (green). Click on image for larger view and links to other scales.

To help compare different distances this section lists lengths starting at 1013 m (10 Tm or 10 billion km or 67 astronomical units).

  • 10 Tm – 67 AU – Diameter of a hypothetical Quasi-star
  • 11.1 Tm – 74.2 AU – Distance that Voyager 1 began detecting returning particles from termination shock
  • 11.4 Tm – 76.2 AU – Perihelion distance of 90377 Sedna
  • 12.1 Tm – 70 to 90 AU – Distance to termination shock (Voyager 1 crossed at 94 AU)
  • 12.9 Tm – 86.3 AU – Distance to 90377 Sedna in March 2014
  • 13.2 Tm – 88.6 AU – Distance to Pioneer 11 in March 2014
  • 14.1 Tm – 94.3 AU – Estimated radius of the solar system
  • 14.4 Tm – 96.4 AU – Distance to Eris in March 2014 (now near its aphelion)
  • 15.1 Tm – 101 AU – Distance to heliosheath
  • 16.5 Tm – 111 AU – Distance to Pioneer 10 as of March 2014
  • 16.6 Tm - 111.2 AU - Distance to Voyager 2 as of May 2016
  • 20.0 Tm - 135 AU - Distance to Voyager 1 as of May 2016
  • 20.6 Tm – 138 AU - Distance to Voyager 1 as of late February 2017
  • 21.1 Tm – 141 AU - Distance to Voyager 1 as of November 2017
  • 25.9 Tm – 172 AU – One light-day
  • 55.7 Tm – 371 AU – Aphelion distance of the comet Hale-Bopp

100 terametres

1e14m comparison light day week and month
The largest yellow sphere indicates one light month distance from the Sun. Click the image for larger view, more details and links to other scales.

To help compare different distances this section lists lengths starting at 1014 m (100 Tm or 100 billion km or 670 astronomical units).

1 petametre

1e15m comparison cat's eye nebula barnard 68 one light year
Largest circle with yellow arrow indicates one light year from Sun; Cat's Eye Nebula on left and Barnard 68 in middle are depicted in front of Comet 1910 A1's orbit. Click image for larger view, details and links to other scales.

To help compare different distances this section lists lengths starting at 1015 m (1 Pm or 1 trillion km or 6685 astronomical units (AU) or 0.11 light years).

10 petametres

1e16m comparison ten light years bubble nebula
Objects with size order of magnitude 1e16m: Ten light years (94.6 Pm) radius circle with yellow Vernal Point arrow; Bubble Nebula (NGC 7635), left; Dumbbell Nebula (NGC 6853), right; one light year shell lower right with the smaller Cat's Eye Nebula (NGC_6543) and Barnard 68 adjacent.
1e16m comparison 10 light years sirius
1e16m lengths: Ten light years (94.6 Pm) yellow shell; Sirius below right; BL Ceti below left; Proxima and Alpha Centauri upper right; light year shell with Comet 1910 A1's orbit inside top right

To help compare different distances this section lists lengths starting at 1016 m (10 Pm or 66,800 AU, 1.06 light years).

  • 15 Pm – 1.59 light years – Possible outer radius of Oort cloud
  • 20 Pm – 2.11 light years – maximum extent of influence of the Sun's gravitational field
  • 30.9 Pm – 3.26 light years – 1 parsec
  • 39.9 Pm – 4.22 light years – Distance to Proxima Centauri (nearest star to Sun)
  • 81.3 Pm – 8.59 light years – Distance to Sirius

100 petametres

1e17m comparison 100 light years nebula clusters
Lengths with order of magnitude 1e17m: yellow Vernal Point arrow traces hundred light year radius circle with smaller ten light year circle at right; globular cluster Messier 5 in background; 12 light year radius Orion Nebula middle right; 50 light year wide view of the Carina Nebula bottom left; Pleiades cluster and Bubble nebula with similar diameters each around 10 light years bottom right; grey arrows show distances from Sun to stars Aldebaran (65 light years) and Vega (25 light years).

To help compare different distances this section lists lengths between 1017 m (100 Pm or 11 light years) and 1018 m (106 light years).

  • 110 Pm – 12 light years – Distance to Tau Ceti
  • 230 Pm – 24 light years – Diameter of the Orion Nebula[146][147]
  • 240 Pm – 25 light years – Distance to Vega
  • 260 Pm – 27 light years – Distance to Chara, a star approximately as bright as our Sun. Its faintness gives us an idea how our Sun would appear when viewed from even so close a distance as this.
  • 350 Pm – 37 light years – Distance to Arcturus
  • 373.1 Pm – 39.44 light years - Distance to TRAPPIST-1, a star recently discovered to have 7 planets around it
  • 400 Pm – 42 light years – Distance to Capella
  • 620 Pm – 65 light years – Distance to Aldebaran
  • 750 Pm - 79.36 light years - Distance to Regulus
  • 900 Pm - 92.73 light years - Distance to Algol

1 exametre

1e18m comparison 1000 light years nebula clusters
Lengths with order of magnitude 1e18m: thousand light year radius circle with yellow arrow and 100 light year circle at right with globular cluster Messier 5 within and Carina Nebula in front; globular cluster Omega Centauri to left of both; part of the 1400 light year wide Tarantula Nebula fills the background.

This list includes distances between 1 and 10 exametres (1018 m). To help compare different distances this section lists lengths between 1018 m (1 Em or 105.7 light years) and 1019 m (1057 light years).

10 exametres

To help compare different orders of magnitude, this section lists distances starting at 10 Em (1019 m or 1,100 light years).

100 exametres

To help compare different orders of magnitude, this section lists distances starting at 100 Em (1020 m or 11,000 light years).

1 zettametre

The zettametre (SI symbol: Zm) is a unit of length in the metric system equal to 1021 metres.[154]

To help compare different orders of magnitude, this section lists distances starting at 1 Zm (1021 m or 110,000 light years).

10 zettametres

To help compare different orders of magnitude, this section lists distances starting at 10 Zm (1022 m or 1.1 million light years).

100 zettametres

To help compare different orders of magnitude, this section lists distances starting at 100 Zm (1023 m or 11 million light years).

1 yottametre

The yottametre, or yottameter in the US, ( SI symbol: Ym) is a unit of length in the metric system equal to 1024 metres[154]

To help compare different orders of magnitude, this section lists distances starting at 1 Ym (1024 m or 105.702 million light years).

10 yottametres

Superclusters atlasoftheuniverse
The universe within 1 billion light years of Earth

To help compare different orders of magnitude, this section lists distances starting at 10 Ym (1025 m or 1.1 billion light-years). At this scale, expansion of the universe becomes significant. Distance of these objects are derived from their measured redshifts, which depends on the cosmological models used.

100 yottametres

To help compare different orders of magnitude, this section lists distances starting at 100 Ym (1026 m or 11 billion light years). At this scale, expansion of the universe becomes significant. Distance of these objects are derived from their measured redshifts, which depend on the cosmological models used.

Distances longer than 100 Ym

  • 130 Ym – redshift 6.41 – 13 billion light years – Light travel distance (LTD) to the quasar SDSS J1148+5251
  • 130 Ym – redshift 1000 – 13.8 billion light years – Distance (LTD) to the source of the cosmic microwave background radiation; radius of the observable universe measured as a LTD
  • 260 Ym – 27.4 billion light years – Diameter of the observable universe (double LTD)
  • 440 Ym – 46 billion light years – Radius of the universe measured as a comoving distance
  • 590 Ym – 62 billion light years – Cosmological event horizon: the largest comoving distance from which light will ever reach us (the observer) at any time in the future
  • 886.48 Ym – 93.7 billion light years – The diameter of the observable universe; however, there might be unobserved distances that are even greater.
  • >1,000 Ym (1 kYm or xennameter in older usage) – Size of universe beyond the cosmic light horizon, depending on its curvature; if the curvature is zero (i.e. the universe is spatially flat), the value can be infinite (see Shape of the universe) as previously mentioned

Notes

  1. ^ The diameter of human hair ranges from 17 to 181 μm Ley, Brian (1999). Elert, Glenn (ed.). "Diameter of a human hair". The Physics Factbook. Retrieved 8 December 2018.
  2. ^ a b The exact category (asteroid, dwarf planet, or planet) to which particular Solar System objects belong, has been subject to some revision since the discovery of extrasolar planets and trans-Neptunian objects
  3. ^ 10115 is 1 followed by 115 zeroes, or a googol multiplied by a quadrillion. 1010115 is 1 followed by a quadrillion googol zeroes. 101010122is 1 followed by 1010122 (a googolplex10 sextillion) zeroes.
  4. ^ But not cloud or high-level fog droplets; droplet size increases with altitude. For a contradictory study indicating larger drop sizes even in ground fog, see Eldridge, Ralph G. (October 1961). "A Few Fog Drop-Size Distributions". Journal of Meteorology. 18 (5): 671–6. Bibcode:1961JAtS...18..671E. doi:10.1175/1520-0469(1961)018<0671:AFFDSD>2.0.CO;2.

See also

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External links

10 AM

10 A.M. or variants may refer to:

A time on the 12-hour clock

"10AM / Save the World", a 2018 song by Metro Boomin featuring Gucci Mane

10 attometres, a very small distance equal to 10−17 metres

Orders of magnitude (length), a comparative scale regime at 10 attometers

1 A.M.

1 A.M. or 1am or variation may refer to:

A time on the 12-hour clock

1 am = 1 attometre (a very small distance)

Orders of magnitude (length), a comparative scale regime at 1 attometer

Aircraftman, 1st class (1AM) in the Royal New Zealand Air Force

Centimetre

A centimetre (international spelling as used by the International Bureau of Weights and Measures; symbol cm) or centimeter (American spelling) is a unit of length in the metric system, equal to one hundredth of a metre, centi being the SI prefix for a factor of 1/100. The centimetre was the base unit of length in the now deprecated centimetre–gram–second (CGS) system of units.

Though for many physical quantities, SI prefixes for factors of 103—like milli- and kilo-—are often preferred by technicians, the centimetre remains a practical unit of length for many everyday measurements. A centimetre is approximately the width of the fingernail of an average adult person.

Decametre

A decametre (International spelling as used by the International Bureau of Weights and Measures) or dekameter (American spelling), symbol dam (sometimes unofficially Dm or dkm), is a unit of length in the metric system equal to ten metres; it is very rarely used.This measure is included in the SI mostly for completeness: in principle, any combination of prefix and unit can be written, but many are rarely used in practice. One practical use of the decametre is for altitude of geopotential heights in meteorology. Meteorologists also use another seldom encountered SI prefix: hecto- in hectopascal (hPa). The volumetric form cubic decametre is convenient for describing large volumes of water such as in rivers and lakes. A cubic decametre (dam3) is equivalent to one megalitre (ML).

The square decametre (dam2), also known as the are (a), is the basis for the hectare (100 dam2), the standard metric unit of land registry.

Decimetre

The decimeter (SI symbol dm) is a unit of length in the metric system, equal to one tenth of a metre (the International System of Units base unit of length), ten centimetres or 3.937 inches.

The common non-SI metric unit of volume, the litre, is defined as one cubic decimetre (however, from 1901 to 1964, there was a slight difference between the two due to the litre being defined with respect to the kilogram rather than the metre).

Fock–Lorentz symmetry

Lorentz invariance follows from two independent postulates: the principle of relativity and the principle of constancy of the speed of light. Dropping the latter while keeping the former leads to a new invariance, known as Fock–Lorentz symmetry or the projective Lorentz transformation. The general study of such theories began with Fock, who was motivated by the search for the general symmetry group preserving relativity without assuming the constancy of c.

This invariance does not distinguish between inertial frames (and therefore satisfies the principle of relativity) but it allows for a varying speed of light in space, c; indeed it allows for a non-invariant c. According to Maxwell's equations, the speed of light satisfies

where ε0 and μ0 are the electric constant and the magnetic constant. If the speed of light depends upon the space–time coordinates of the medium, say x, then

where represents the vacuum as a variable medium.

Hectometre

The hectometre (International spelling as used by the International Bureau of Weights and Measures; SI symbol: hm) or hectometer (American spelling) is an uncommonly used unit of length in the metric system, equal to one hundred metres. The word comes from a combination of "metre" and the SI prefix "hecto-", meaning "hundred". A soccer field is approximately 1 hectometre in length. The hectare (ha), a common metric unit for land area, is equal to one square hectometre (hm2).

Index of physics articles (O)

The index of physics articles is split into multiple pages due to its size.

To navigate by individual letter use the table of contents below.

Kilometre

The kilometre, (International spelling as used by the International Bureau of Weights and Measures; SI symbol: km; or ) or kilometer (American spelling) is a unit of length in the metric system, equal to one thousand metres (kilo- being the SI prefix for 1000). It is now the measurement unit used officially for expressing distances between geographical places on land in most of the world; notable exceptions are the United States and the road network of the United Kingdom where the statute mile is the official unit used.

k (pronounced ) is occasionally used in some English-speaking countries as an alternative for the word kilometre in colloquial writing and speech. A slang term for the kilometre in the US and UK military is klick.

Length

Length is a measure of distance. In the International System of Quantities, length is any quantity with dimension distance. In most systems of measurement, the unit of length is a base unit, from which other units are derived.

In geometry, length is the most extended dimension of an object.Length may be distinguished from height, which is vertical extent, and width or breadth, which are the distance from side to side, measuring across the object at right angles to the length.

Length is a measure of one dimension, whereas area is a measure of two dimensions (length squared) and volume is a measure of three dimensions (length cubed).

Length scale

In physics, length scale is a particular length or distance determined with the precision of one order of magnitude. The concept of length scale is particularly important because physical phenomena of different length scales cannot affect each other[citation needed][clarification needed] and are said to decouple. The decoupling of different length scales makes it possible to have a self-consistent theory that only describes the relevant length scales for a given problem. Scientific reductionism says that the physical laws on the shortest length scales can be used to derive the effective description at larger length scales. The idea that one can derive descriptions of physics at different length scales from one another can be quantified with the renormalization group.

In quantum mechanics the length scale of a given phenomenon is related to its de Broglie wavelength where is the reduced Planck's constant and is the momentum that is being probed. In relativistic mechanics time and length scales are related by the speed of light. In relativistic quantum mechanics or relativistic quantum field theory, length scales are related to momentum, time and energy scales through Planck's constant and the speed of light. Often in high energy physics natural units are used where length, time, energy and momentum scales are described in the same units (usually with units of energy such as GeV).

Length scales are usually the operative scale (or at least one of the scales) in dimensional analysis. For instance, in scattering theory, the most common quantity to calculate is a cross section which has units of length squared and is measured in barns. The cross section of a given process is usually the square of the length scale.

Light-year

The light-year is a unit of length used to express astronomical distances and measures about 9.46 trillion kilometres (9.46 x 1012 km) or 5.88 trillion miles (5.88 x 1012 mi). As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in vacuum in one Julian year (365.25 days). Because it includes the word "year", the term light-year is sometimes misinterpreted as a unit of time.

The light-year is most often used when expressing distances to stars and other distances on a galactic scale, especially in nonspecialist and popular science publications. The unit most commonly used in professional astrometry is the parsec (symbol: pc, about 3.26 light-years; the distance at which one astronomical unit subtends an angle of one second of arc).

Micrometre

The micrometre (International spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known by the previous name micron, is an SI derived unit of length equalling 1×10−6 metre (SI standard prefix "micro-" = 10−6); that is, one millionth of a metre (or one thousandth of a millimetre, 0.001 mm, or about 0.000039 inch).The micrometre is a common unit of measurement for wavelengths of infrared radiation as well as sizes of biological cells and bacteria, and for grading wool by the diameter of the fibres. The width of a single human hair ranges from approximately 10 to 200 μm. The longest human chromosome is approximately 10 μm in length.

Millimetre

The millimetre (international spelling as used by the International Bureau of Weights and Measures; SI unit symbol mm) or millimeter (American spelling) is a unit of length in the metric system, equal to one thousandth of a metre, which is the SI base unit of length. Therefore, there are one thousand millimetres in a metre. There are ten millimetres in a centimetre.

One millimetre is equal to 1000 micrometres or 1000000 nanometres. A millimetre is equal to exactly ​5⁄127 (approximately 0.039370) of an inch, which is officially defined as exactly 25.4 millimetres.

Nautical mile

A nautical mile is a unit of measurement used in both air and marine navigation, and for the definition of territorial waters. Historically, it was defined as one minute (1/60) of a degree of latitude. Today it is defined as exactly 1852 metres. The derived unit of speed is the knot, one nautical mile per hour.

Picometre

The picometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: pm) or picometer (American spelling) is a unit of length in the metric system, equal to 1×10−12 m, or one trillionth (1/1000000000000) of a metre, which is the SI base unit of length.

The picometre is one thousandth of a nanometre, one millionth of a micrometre (also known as a micron), and used to be called micromicron, stigma, or bicron. The symbol µµ was once used for it. It is also one hundredth of an Ångström, an internationally recognised (but non-SI) unit of length.

Solar radius

Solar radius is a unit of distance used to express the size of stars in astronomy relative to the Sun. The solar radius is usually defined as the radius to the layer in the Sun's photosphere where the optical depth equals 2/3:

695,700 kilometres (432,300 miles) is approximately 10 times the average radius of Jupiter, about 109 times the radius of the Earth, and 1/215th of an astronomical unit, the distance of the Earth from the Sun. It varies slightly from pole to equator due to its rotation, which induces an oblateness in the order of 10 parts per million.

Spatial scale

In sciences such as physics, geography, astronomy, meteorology and statistics, the term scale or spatial scale is used for describing or classifying with large approximation the extent or size of a length, distance or area studied or described. For instance, in physics an object or phenomenon can be called microscopic if too small to be visible. In climatology, a micro-climate is a climate which might occur in a mountain, valley or near a lake shore, whereas in statistics a megatrend is a political, social, economical, environmental or technological trend which involves the whole planet or is supposed to last a very large amount of time.

In physics, the concept of scale is closely related to the more accurate concept of order of magnitude.

These divisions are somewhat arbitrary; where, on this table, mega- is assigned global scope, it may only apply continentally or even regionally in other contexts. The interpretations of meso- and macro- must then be adjusted accordingly.

Unit of length

A unit of length refers to any discrete, pre-established length or distance having a constant magnitude which is used as a reference or convention to express linear dimension. The most common units in modern use are U.S. customary units in the United States and metric units elsewhere. British Imperial units are still used for some purposes in the United Kingdom and some other countries. The metric system is sub-divided into SI and non-SI units.

Quantity
See also
Related

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