Since 2019, defined as the length of the path travelled by light in a vacuum during a time interval of 1/299,792,458 of a second, where the second is defined by a hyperfine transition frequency of caesium.
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[52] It equivalently implies that there are at minimum 21 particle horizon-sized volumes in the universe.
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.[53][54]
1.6 × 10−5 quectometres (1.6 × 10−35 metres) – the Planck length (Measures of distance shorter than this do not make physical sense, according to current theories of physics.)
1 qm – 1 quectometre, the smallest named subdivision of the metre in the SI base unit of length, one nonillionth of a metre.[56]
To help compare different orders of magnitude, this section lists lengths between 10−13m 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
The nanometre (SI symbol: nm) is a unit of length in the metric system equal to 10−9metres (1/1000000000m=0.000000001m).
To help compare different orders of magnitude, this section lists lengths between 10−9 and 10−8 m (1nm and 10nm).
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.[68]
200nm – typical size of a Mycoplasma bacterium, among the smallest bacteria
300nm – greatest particle size that can fit through a HEPA (high efficiency particulate air) filter (N100 removes up to 99.97% at 300 nm, N95 removes up to 95% at 300 nm)[73]
To help compare different orders of magnitude, this section lists lengths between 10−4m and 10−3 m (100μm and 1mm). The term myriometre (abbr. mom, equivalent to 100 micrometres; frequently confused with the myriametre, 10 kilometres)[86] is deprecated; the decimal metric prefix myrio-[87] is obsolete[88][89][90] and was not included among the prefixes when the International System of Units was introduced in 1960.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 – 0.00394inches
100 μm – smallest distance that can be seen with the naked eye
Leonardo da Vinci drew the Vitruvian Man within a square of side 1.83m (6ft 0in) and a circle about 1.2m (3ft 11in) in radius
To help compare different orders of magnitude, this section lists lengths between one metre and ten metres.
Light, in vacuum, travels 1 metre in 1⁄299,792,458, or 3.3356409519815E-9 of a second.
1.63 m – (5 feet 4 inches) (or 64 inches) – height of average U.S. female human as of 2002[update] (source: U.S. Centers for Disease Control and Prevention (CDC))
1.75 m – (5 feet 8 inches) – height of average U.S. male human as of 2002[update] (source: U.S. CDC as per female above)
15 metres – approximate distance the tropical circles of latitude are moving towards the equator and the polar circles are moving towards the poles each year due to a natural, gradual decrease in the Earth's axial tilt
16 metres – length of a sperm whale, the largest toothed whale
18 metres – height of a Sauroposeidon, the tallest-known dinosaur
20 metres – length of a Leedsichthys, the largest-known fish to have lived
21 metres – height of High Force waterfall in England
30.5 metres – length of the lion's mane jellyfish, the largest jellyfish in the world
33 metres – length of a blue whale,[114] the largest animal on earth, living or extinct, in terms of mass
39 metres – length of a Supersaurus, the longest-known dinosaur and longest vertebrate[115]
84 metres – height of General Sherman, the largest tree in the world
Astronomical
30 metres – diameter of 1998 KY26, a rapidly spinning meteoroid
30.8568 metres – 1 femtoparsec
32 metres – approximate diameter of 2008 HJ, a small meteoroid
The Great Pyramid of Giza is 138.8m (455ft) high.British driver location sign and location marker post on the M27 in Hampshire. The location marker posts are installed at 100-metre intervals.[117]
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.
Small planets, the Moon and dwarf planets in the 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.
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
This section needs additional citations for verification. (April 2007)
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.Scale model at megametres of the main Solar System bodies.
; lower part: their darker mirror images (artist's interpretation).
The gigametre (SI symbol: Gm) is a unit of length in the metric system equal to 1000000000metres (109m).
To help compare different distances this section lists lengths starting at 109metres (1 gigametre (Gm) or 1 billion metres).
5.0 Gm – Closest approach of Comet Halley to Earth, happened on 10 April 837
5.0 Gm – (proposed) Size of the arms of the giant triangle shaped Michelson interferometer of the Laser Interferometer Space Antenna (LISA) planned to start observations sometime in the 2030s.
7.9 Gm – Diameter of Gamma Orionis, a blue dwarf or blue giant
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.
35 Gm – Approximate diameter of Arcturus, a close red giant star.[162] It is on the red giant branch, fusing hydrogen into helium in a shell surrounding an inert helium core.[161]
46 Gm – Perihelion distance of Mercury (yellow ellipse on the right)
55 Gm – 60,000-year perigee of Mars (last achieved on 27 August 2003)
58 Gm – Average passing distance between Earth and Mars at the moment they overtake each other in their orbits
61 Gm – Diameter of Aldebaran, a red giant branch star (large star on right)[163]
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's depiction are the blue supergiant 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.
280 Gm (1.9 au) – Approximate diameter of Deneb, a blue supergiant and the brightest star in the Cygnus constellation[166]
511 Gm (3.4 au) – Average diameter of Mira, a pulsating red giant and the progenitor of the Mira variables. It is an asymptotic giant branch star, fusing carbon into neon in a shell surrounding an inert core.[167]
570 Gm (3.8 au) – Length of the tail of Comet Hyakutake measured by Ulysses; the actual value could be much higher
965 Gm (6.4 au) – Maximum distance between the Earth and Jupiter
8 things in the terametre groupComparison 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.
7.5 Tm – 50.1 au – Outer radius of the Kuiper Belt
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 1013m (10 Tm or 10 billion km or 67 astronomical units).
10 Tm – 67 AU – Diameter of a hypothetical quasi-star
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.
7.5 Pm – 50,000 AU – Possible outer boundary of Oort cloud (other estimates are 75,000 to 125,000 or even 189,000 AU (1.18, 2, and 3 light-years, respectively))
9.5 Pm – 63,241.1 AU – One light-year, the distance traveled by light in one year
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 section lists lengths starting at 1016m (10 Pm or 66,800 AU, 1.06 light-years).
15 Pm – 1.59 light-years – Possible outer radius of Oort cloud
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 1017m (100 Pm or 11 light-years) and 1018 m (106 light-years).
260 Pm – 27 light-years – Distance to Chara, a star approximately as bright as the Sun. Its faintness gives an idea how the Sun would appear when viewed from this distance.
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 1,400-light-year-wide Tarantula Nebula fills the background.
The exametre (SI symbol: Em) is a unit of length in the metric system equal to 1018metres. To help compare different distances this section lists lengths between 1018m (1Em or 105.7 light-years) and 1019m (10Em or 1,057 light-years).
The universe within one billion light-years of Earth
To help compare different orders of magnitude, this section lists distances starting at 10 Ym (1025m 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.
13 Ym – 1.37 billion light-years – Length of the South Pole Wall
13 Ym – 1.38 billion light-years – Length of the Sloan Great Wall
To help compare different orders of magnitude, this section lists distances starting at 100 Ym (1026m 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.
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 (twice the particle horizon); however, there might be unobserved distances that are even greater.
To help compare different orders of magnitude, this section lists distances starting at 1 Rm (1027m or 110 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.
>1 Rm – >105.7 billion light-years – 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
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.
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
10115 is 1 followed by 115 zeroes, or a googol multiplied by a quadrillion. 1010115 is 1 followed by a quadrillion googol zeroes. 101010122 is 1 followed by 1010122 (a googolplex10 sextillion) zeroes.
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