Orders of magnitude (length)

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


Section Range (m) Unit Example Items
Planck length 10−35 P Quantum foam
Subatomic 10−35 10−15 am Electron, quark, string
Atomic and 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
Human scale 10−6 10−3 μm Bacterium, fog water droplet, human hair's diameter[1]
10−3 100 mm Mosquito, golf ball, domestic cat, violin, football
100 103 m Cello, human, automobile, sperm whale, football field, Eiffel Tower
103 106 km Walt Disney World, 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 One light-year; 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 1.6×10−35 meters and meters.


Factor (m) Multiple Value Item
10−35 1 Planck Length 0.0000000000162 ym (1.62×10−35 m) 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.[2] Quantum foam is thought to exist at this level.
10−24 1 yoctometer (ym) 20 ym (2 × 1023 meters) Effective cross section radius of 1 MeV neutrinos[3]
10−21 1 zeptometer (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 (7 × 1021 meters) Effective cross section radius of high energy neutrinos[4]
310 zm (3.10 × 1019 meters) De Broglie wavelength of protons at the Large Hadron Collider (4 TeV as of 2012)
10−18 1 attometer (am) Upper limit for the size of quarks and electrons
Sensitivity of the LIGO detector for gravitational waves[5]
Upper bound of the typical size range for "fundamental strings"[2]
10−17 10 am Range of the weak force
10−16 100 am 850 am approximate proton radius[6]

Atomic to cellular

Factor (m) Multiple Value Item

10−15 1 femtometer (fm) 1.5 fm Size of an 11 MeV proton[7]
2.81794 fm Classical electron radius[8]
Scale of the atomic nucleus[2][9]
10−12 1 picometer (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 25 pm Radius of hydrogen atom
31 pm Radius of helium atom
53 pm Bohr radius
10−10 100 pm 100 pm (0.1 nm) 1 Ångström (also covalent radius of sulfur atom[10])
154 pm (0.154 nm) Length of a typical covalent bond (C–C).
500 pm (0.50 nm) Width of protein α helix

10−9 1 nanometer (nm) 1 nm Diameter of a carbon nanotube[11]
2 nm Diameter of the DNA helix[12]
2.5 nm Smallest microprocessor transistor gate oxide thickness (as of Jan 2007)
3.4 nm Length of a DNA turn (10 bp)[13]
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 nanometer was the smallest semiconductor device fabrication node[14]
40 nm Extreme ultraviolet wavelength
50 nm Flying height of the head of a hard disk.[15]
10−7 100 nm 121.6 nm Wavelength of the Lyman-alpha line[16]
120 nm Typical diameter of the human immunodeficiency virus (HIV)[17]
400–700 nm Approximate wavelength range of visible light[18]

Cellular to human scale

Factor (m) Multiple Value Item

10−6 1 micrometer (μm)

(also called one micron)

1–4 μm Typical length of a bacterium.[19]
4 μm Typical diameter of spider silk.[20]
7 μm Typical size of a red blood cell.[21]
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. [1]
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 millimeter (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.
5.56 mm Width of the standard ammunition cartridge 5.56×45mm NATO.
10−2 1 centimeter (cm) 2 cm Approximate width of an adult human finger.
5.4 cm x 8.6 cm Dimensions of a credit card, according to the ISO/IEC 7810 ID-1 standard.
7.3–7.5 cm Diameter of a baseball, according to Major League Baseball guidelines.[24]
10−1 1 decimeter (dm) 1.2 dm = 12 cm Diameter of a Compact Disk.
9 dm = 90 cm Average length of a rapier, a fencing sword.[25]
6.6 dm = 66 cm Length of the longest pine cones, produced by the sugar pine.[26]

Human scale

Factor (m) Multiple Value Item

100 1 meter 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 (8 feet 11 inches) height of Robert Wadlow, tallest known human being.[27]
8.38 m The length of a London Bus (Routemaster).
101 1 decameter (dam) 10 m Wavelength of the lowest VHF and highest shortwave radio frequency, 30 MHz
33 m Length of longest blue whale measured, the largest animal[28]
93.47 m Height of the Statue of Liberty (foundation of pedestal to torch)
102 1 hectometer (hm) 100 m Wavelength of the lowest shortwave radio frequency and highest medium wave radio frequency, 3 MHz
137 m (147 m) Height (present and original) of the Great Pyramid of Giza
828 m Height of the Burj Khalifa, the world's tallest man-made building.
979 m Height of the Salto Angel, the world's highest free-falling waterfall (Venezuela)
103 1 kilometer (km) 1 km Wavelength of the lowest medium wave radio frequency, 300 kHz
1.609 km 1 statute mile
1.852 km 1 nautical mile
8.848 km Height of the highest mountain on Earth, Mount Everest
104 10 km 10.911 km Depth of deepest part of the ocean, Mariana Trench
13 km Narrowest width of the Strait of Gibraltar, separating Europe and Africa
90 km Width of the Bering Strait
105 100 km 111 km Distance covered by one degree of latitude on Earth's surface
163 km Length of the Suez Canal
974.6 km Greatest diameter[29] of the dwarf planet[note 1] Ceres


Factor (m) Multiple Value Item

106 1,000 km = 1 megameter (Mm) 2,390 km Diameter of dwarf planet Pluto, formerly the smallest planet category[note 1] in the Solar System
3,480 km Diameter of the Moon
5,200 km Typical distance covered by the winner of the 24 Hours of Le Mans automobile endurance race
6,400 km Length of the Great Wall of China
6,600 km Approximate length of the two longest rivers, the Nile and the Amazon
7,821 km Length of the Trans-Canada Highway
9,288 km Length of the Trans-Siberian Railway, longest in the world

107 10,000 km 12,756 km Equatorial diameter of Earth
40,075 km Length of Earth's equator

108 100,000 km 142,984 km Diameter of Jupiter
299,792.458 km Distance traveled by light in one second
384,000 km = 384 Mm Moon's orbital distance from Earth

109 1 million km = 1 gigameter (Gm) 1,390,000 km = 1.39 Gm Diameter of the Sun
4,800,000 km = 4.8 Gm Greatest mileage ever recorded by a car (3 million miles by a 1966 Volvo P-1800S, still driving)

1010 10 million km 18 million km Approximately one light-minute

1011 100 million km 150 million km = 150 Gm 1 astronomical unit (AU); mean distance between Earth and Sun
~ 900 Gm Optical diameter of Betelgeuse (~600 × Sun)

1012 1000 million km = 1 terameter (Tm) 1.4 ×109 km Orbital distance of Saturn from Sun
1.96 ×109 km Estimated optical diameter of VY Canis Majoris (1420 × Sun)
2.3 ×109 km Estimated optical diameter of NML Cygni (1650 × Sun)
2.37 ×109 km Median point of the optical diameter of UY Scuti, as of 2014 the largest known star
5.9 ×109 km = 5.9 Tm Orbital distance of Pluto from Sun
~ 7.5 ×109 km = 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[2]
16.25×109 km = 16.25 Tm Distance of the Voyager 1 spacecraft from Sun (as of Feb 2009), the farthest man-made object so far[30]
62.03×109 km = 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 1.8×1011 km = 180 Tm Size of the debris disk around the star 51 Pegasi [31]
2×1011 km = 200 Tm Total length of DNA molecules in all cells of an adult human body [32]
1015 1 petameter (Pm) ~ 7.5 ×1012 km = 7.5 Pm Supposed outer boundary of the Oort cloud (~ 50,000 AU)
9.46×1012 km = 9.46 Pm
= 1 light year
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 3.2616 light-years
(3.0857×1013 km = 30.857 Pm)
1 parsec
4.22 light-years = 39.9 Pm Distance to nearest star (Proxima Centauri)
4.37 light-years = 41.3 Pm As of March 2013, distance to nearest discovered extrasolar planet (Alpha Centauri Bc)

1017 100 Pm 20.4 light-years = 193 Pm As of October 2010, distance to nearest discovered extrasolar planet with potential to support life as we know it (Gliese 581 d)
65 light-years = 6.15×1017 m = 615 Pm Approximate radius of humanity's radio bubble, caused by high-power TV broadcasts leaking through the atmosphere into outer space

1018 1 exameter (Em) 200 light-years = 1.9 Em Distance to nearby solar twin (HIP 56948), a star with properties virtually identical to our Sun [33]

1019 10 Em 1,000 light-years = 9.46 Em or 9.46 × 1015 km Average thickness of Milky Way Galaxy[34] (1000 to 3000 ly by 21 cm observations[35])

1020 100 Em 12,000 light-years = 113.5 Em or 1.135 × 1017 km Thickness of Milky Way Galaxy's gaseous disk[36]
950 Em 100,000 light-years Diameter of galactic disk of Milky Way Galaxy[2]

1021 1 zettameter (Zm)
50 kiloparsecs Distance to SN 1987A, the most recent naked eye supernova
52 kiloparsecs = 1.62×1021 m = 1.62 Zm Distance to the Large Magellanic Cloud (a dwarf galaxy orbiting the Milky Way)
54 kiloparsecs = 1.66 Zm Distance to the Small Magellanic Cloud (another dwarf galaxy orbiting the Milky Way)
200 kiloparsecs = 6.15 Zm Diameter of the low surface brightness disc halo of the giant spiral galaxy Malin 1

1022 10 Zm 13.25 Zm = 1.4 million light years
= 600 kiloparsecs
Radius of the diffuse stellar halo of IC 1101, one of the largest known galaxies
24 Zm = 2.5 million light-years
= 770 kiloparsecs
Distance to Andromeda Galaxy
3.26 million light-years
=30.8 Zm = 1 megaparsec
1 megaparsec
50 Zm (1.6 Mpc) Diameter of Local Group of galaxies

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1023 100 Zm 300–600 Zm = 10–20 megaparsecs Distance to Virgo cluster of galaxies

1024 1 yottameter (Ym) 200 million light-years
= 1.9 Ym = 61 megaparsecs
Diameter of the Local Supercluster and the largest voids and filaments.
300 million light-years
= 2.8 Ym = 100 megaparsecs
End of Greatness
550 million light-years
~170 megaparsecs ~5 Ym
Diameter of the enormous Horologium Supercluster [37]

1 billion light-years
= 9.46 Ym =306 megaparsecs
Diameter of the Pisces–Cetus Supercluster Complex, the supercluster complex where we live.
1025 10 Ym 1.37 billion light years
= 1.3×1025 m = 13 Ym
Length of the Sloan Great Wall, a giant wall of galaxies (galactic filament).[38]
3.26 billion light years
=30.8 Ym = 1 gigaparsec
1 gigaparsec
4 billion light years
=37.84 Ym
Length of the Huge-LQG, a group of 73 quasars
1026 100 Ym 1×1010 light-years
= 9.5×1025 m = 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.
13.42 billion light years
=1.27×1026 m = 127 Ym
Estimated light travel distance to UDFj-39546284, the most distant object ever observed
9.2×1010 light years
= 8.7×1026 m = 870 Ym
Approximate diameter (comoving distance) of the visible universe[2]
1027 1000 Ym 130 billion light years
= 1.2×1027 m = 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.[39] It equivalently implies that there are at minimum 21 particle horizon-sized volumes in the universe.
[note 2] Ym megaparsecs
=  m
= 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.[40][41]
[note 2] Ym Mpc
=  m
= Ym
Maximum size of universe after cosmological inflation, implied by one resolution of the No-Boundary Proposal[42]

1 decametre

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 page lists lengths between 10 metres and 100 metres.


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

Human-defined scales and structures




1 hectometre

The Great Pyramid of Giza is 138.8 metres high.
British driver location sign and location marker post on the M27 in Hampshire. The location marker posts are installed at 100-metre intervals[47]

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


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

Human-defined scales and structures




1 kilometre

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

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


1 kilometre (unit symbol km) is equal to:

Human-defined scales and structures



1 myriametre

The Strait of Gibraltar is 13 kilometres wide

To help compare different orders of magnitude this page lists lengths between 10 and 100 kilometres (104 to 105 metres). The myriametre[65] (sometimes also spelled myriameter, myriometre and myriometer) (10,000 metres) is a deprecated unit name; the decimal metric prefix myria-[66] (sometimes also written as myrio-[67][68][69]) is obsolete[70][71][72] and not included among the prefixes when the International System of Units was introduced in 1960.


10 kilometres is equal to:

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


Human-defined scales and structures



100 kilometres

The Suez Canal is 163 kilometres long

A length of 100 kilometers (about 62 English 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 page lists lengths between 100 and 1,000 kilometres (105 and 106 metres).


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

Human-defined scales and structures



1 megametre

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 page lists lengths starting at 106 m (1 Mm or 1,000 km).


1 megametre is equal to:

Human-defined scales and structures




10 megametres

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 page lists lengths starting at 107 metres (10 megametres or 10,000 kilometres).


10 megametres (10 Mm) is

Human-defined scales and structures



100 megametres

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 page lists lengths starting at 108 metres (100 megametres or 100,000 kilometres or 62,150 miles).

1 gigametre

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 page lists lengths starting at 109 metres (1 gigametre (Gm) or 1 billion metres).

10 gigametres

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: click image for larger view and links to other scales.

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

100 gigametres

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 page lists lengths starting at 1011 metres (100 Gm or 100 million kilometres or 0.7 astronomical units).

1 terametre

8 things in the Terameter group
Comparison of size of the Kuiper belt (large faint torus) with the star VY Canis Majoris (at its previous estimate, 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 page lists lengths starting at 1012 m (1 Tm or 1 billion km or 6.7 astronomical units). Less than 1 Terameter from earth to the Sun

10 terametres

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 page lists lengths starting at 1013 m (10 Tm or 10,000 million km or 67 astronomical units).

100 terametres

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.
This list is incomplete; you can help by expanding it.

To help compare different distances this page lists lengths starting at 1014 m (100 Tm or 100,000 million km or 670 astronomical units).

1 petametre

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 page lists lengths starting at 1015 m (1 Pm or 1,000,000 million km or 6685 astronomical units (AU) or 0.11 light years).

10 petametres

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 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 page lists lengths starting at 1016 m (10 Pm or 66,800 AU, 1.06 light years).

100 petametres

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).
This list is incomplete; you can help by expanding it.

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

1 exametre

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 page 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 page lists distances starting at 10 Em (1019 m or 1,100 light years).

100 exametres

To help compare different orders of magnitude, this page 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.[108]

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

10 zettametres

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

100 zettametres

To help compare different orders of magnitude, this page 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[108]

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

10 yottametres

The universe within 1 billion light years of Earth

To help compare different orders of magnitude, this page 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 page lists distances greater than 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 depends on the cosmological models used.

Distances longer than 100 Ym


  1. 1 2 3 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
  2. 1 2 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.


  1. 1 2 According to The Physics Factbook, the diameter of human hair ranges from 17 to 181 μm. Ley, Brian (1999). "Width of a Human Hair". The Physics Factbook.
  2. 1 2 3 4 5 6 Cliff Burgess; Fernando Quevedo (November 2007). "The Great Cosmic Roller-Coaster Ride". Scientific American (print). Scientific American, Inc. p. 55.
  3. Carl R. Nave. "Cowan and Reines Neutrino Experiment". Retrieved 2008-12-04. (6.3 × 1044 cm2, which gives an effective radius of about 2 × 1023 m)
  4. Carl R. Nave. "Neutron Absorption Cross-sections". Retrieved 2008-12-04. (area for 20 GeV about 10 × 1042 m2 gives effective radius of about 2 × 1021 m; for 250 GeV about 150 × 1042 m2 gives effective radius of about 7 × 1021 m)
  5. gravitational waves that originate tens of millions of light years from Earth are expected to distort the 4 kilometer mirror spacing by about 10−18 m, less than one-thousandth the charge diameter of a proton. Equivalently, this is a relative change in distance of approximately one part in 1021. "On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10−21." B. P. Abbott et al. (LIGO Scientific Collaboration and Virgo Collaboration), "Observation of Gravitational Waves from a Binary Black Hole Merger", Phys. Rev. Lett. 116, 061102, published 11 February 2016.
  6. Randolf Pohl; Aldo Antognini; François Nez; Fernando D. Amaro; François Biraben; João M. R. Cardoso; Daniel S. Covita; Andreas Dax; Satish Dhawan; Luis M. P. Fernandes; Adolf Giesen; Thomas Graf; Theodor W. Hänsch; Paul Indelicato; Lucile Julien; Cheng-Yang Kao; Paul Knowles; Eric-Olivier Le Bigot; Yi-Wei Liu; José A. M. Lopes; Livia Ludhova; Cristina M. B. Monteiro; Françoise Mulhauser; Tobias Nebel; Paul Rabinowitz; et al. (8 July 2010). "The size of the proton". Nature. 466 (7303): 213–216. Bibcode:2010Natur.466..213P. doi:10.1038/nature09250. PMID 20613837. Retrieved 2010-07-09.
  7. Carl R. Nave. "Scattering Cross Section". Retrieved 2009-02-10. (diameter of the Scattering Cross Section of an 11 MeV proton with a target proton)
  8. NIST. CODATA Value: classical electron radius. Retrieved 2009-02-10
  9. H. E. Smith. "The Scale of the Universe". UCSD. Retrieved 2009-02-10. ~10−13cm
  10. Mark Winter (2008). "WebElements Periodic Table of the Elements / Sulfur / Radii". Retrieved 2008-12-06.
  11. Flahaut, E.; Bacsa R; Peigney A; Laurent C. (2003). "Gram-Scale CCVD Synthesis of Double-Walled Carbon Nanotubes". Chemical Communications. 12 (12): 1442–1443. doi:10.1039/b301514a. PMID 12841282. Retrieved 2008-11-14.
  12. Stewart, Robert. "Dr.". Radiobiology Software. Archived from the original on 2010-06-30. Retrieved 2015-05-20.
  13. Dominique Langevin. "Chapter 10: DNA-Surfactant/Lipid Complexes at Liquid Interfaces". In Rita S Dias and Bjorn Lindman. DNA Interactions with Polymers and Surfactants (PDF). Hoboken, NJ: John Wiley & Sons, Inc. p. 265. ISBN 978-0-470-25818-7. Retrieved 24 May 2014. DNA has 20 elementary charges per helical turn over the corresponding length of 3.4nm
  14. helpwithpcs.com http://www.helpwithpcs.com/hardware/hard-drive-basics.php. Retrieved 13 July 2016. Missing or empty |title= (help)
  15. Cohn, J. University of California, Berkeley Lyman alpha systems and cosmology. Retrieved 2009-02-21
  16. Seth, S.D.; Seth, Vimlesh (2009). Textbook of Pharmacology (3rd ed.). Elsevier. p. X111. ISBN 978-81-312-1158-8. Retrieved 19 July 2016.
  17. Color
  18. "Size of bacteria". What are bacteria?. Retrieved 19 July 2016.
  19. "Engineering properties of spider silk" (PDF). web.mit.edu. Retrieved 19 July 2016.
  20. Doohan, Jim. "Blood cells". biosbcc.net. Retrieved 19 July 2016.
  21. "Evaluation of corneal thickness and topography in normal eyes using the Orbscan corneal topography system". Br J Ophthalmol. 83 (7): 774–8. July 1999. doi:10.1136/bjo.83.7.774. PMC 1723104Freely accessible. PMID 10381661.
  22. Order Siphonaptera – Fleas – BugGuide.Net Accessed 29 April 2014
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