{{3.14159}{3.14159}{3.14159}{3.14159}{3.14159}{3.14159}} the speed of light

{{3.14159}{3.14159}{3.14159}{3.14159}{3.14159}{3.14159}} the speed of light

24000/{3.14159} = the sound of time echoing off an empty orb walled in around

7639.44372117 diameter of the blue ball of fear called some slimes the smurf others earth

the time of the splay at 7639 is other than the time of the flay at 24000/3 = 8000

the equation solved by the ringing in your ears as your empty bag of salt water

blasts through the bladder of the uni vers us ~66000 miles per tomorrow in base 3

7917.5 according to a tape measure which takes a lickin and keeps on ticken

implying 24000/7927.5 = 3.02743614002 a box with a few sides too few

to roll the way a big bald head appears to pop over the line every once

in a 360 degree revolution of non sense ideas blown with the wind

in to the solar amniotic fluid which at the density of the uni is the

verse that keeps the gears oiled with fishy water and the eyes

well tuned to the sound of carrots munching 31.4159 mach

at the local open 24000 miles per mothers milk later

sooner then when two morrow equal one yester

day the way that can not be named as the

way other than the one which is the en

diagonal beginning of all tri angular

ponts of reference to every (())π

ΗΣΓ ΣΣΠ οΧ complete {{[[((]]

00}} {}{}^(()) ΣΕΠΣ

imperial & US units	9.2956 μιλ

(93 million miles) or 8.3 light minutes. The actual distance from Earth to the Sun varies by about 3% as Earth orbits the Sun, from a maximum (aphelion) to a minimum (perihelion) and back again once each year. The astronomical unit was originally conceived as the average of Earth's aphelion and perihelion; however, since 2012 it has been defined as exactly 149597870700 m (see below for several conversions).^[5]

   9 / ξ.1 5  = 93 / (31.4159-.4159) = 3

Earth radius
Cross section of Earth's Interior
General information
Unit system	astronomy, geophysics
Unit of	distance
Symbol	R🜨 or ${\displaystyle R_{E}}$, ${\displaystyle {\mathcal {R}}_{\mathrm {eE} }^{\mathrm {N} }}$
Conversions
1 R🜨 in ...	... is equal to ...
	English units    3,950 to 3,963 mi = diameter of between 8000 or 24/3 and 395*2=7900

Sun 

True-color image taken in 2019 using a solar filter
Names	Sun, Sol /ˈsɒl/,[1] Sól, Helios /ˈhiːliəs/[2]
Adjectives	Solar /ˈsoʊlər/[3]
Observation data
Mean distance from Earth	1 AU ≈ 1.496×108 km[4] 8 min 19 s at light speed
Visual brightness (V)	−26.74[5]
Absolute magnitude	4.83[5]
Spectral classification	G2V[6]
Metallicity	Z = 0.0122[7]
Angular size	31.6–32.7 minutes of arc[8] 0.527–0.545 degrees
Orbital characteristics
Mean distance from Milky Way core	≈2.7×1017 km ≈29,000 light-years
Galactic period	(2.25–2.50)×108 yr
Velocity	≈251 km/s (orbit around the center of the Milky Way) ≈ 20 km/s (relative to average velocity of other stars in stellar neighborhood) ≈ 370 km/s[9] (relative to the cosmic microwave background)
Physical characteristics
Equatorial radius	695,700 km,[10] 696,342 km[11] 109 × Earth radii[12]
Equatorial circumference	4.379×106 km[12] 109 × Earth[12]
Flattening	9×10−6
Surface area	6.09×1012 km2[12] 12,000 × Earth[12]
Volume	1.41×1018 km3[12] 1,300,000 × Earth
Mass	1.9885×1030 kg[5] 332,950 Earths[5]
Average density	1.408 g/cm3[5][12][13] 0.255 × Earth[5][12]
Center density (modeled)	162.2 g/cm3[5] 12.4 × Earth
Equatorial surface gravity	274 m/s2[5] 28 × Earth[12]
Moment of inertia factor	0.070[5] (estimate)
Escape velocity (from the surface)	617.7 km/s[12] 55 × Earth[12]
Temperature	Center (modeled): 1.57×107 K[5] Photosphere (effective): 5,772 K[5] Corona: ≈ 5×106 K
Luminosity (Lsol)	3.828×1026 W[5] ≈ 3.75×1028 lm ≈ 98 lm/W efficacy
Color (B-V)	0.63
Mean radiance (Isol)	2.009×107 W·m−2·sr−1
Age	≈4.6 billion years (4.6×109 years)[14][15]
Photospheric composition (by mass)	73.46% hydrogen[16] 24.85% helium 0.77% oxygen 0.29% carbon 0.16% iron 0.12% neon 0.09% nitrogen 0.07% silicon 0.05% magnesium 0.04% sulphur
Rotation characteristics
Obliquity	7.25°[5] (to the ecliptic) 67.23° (to the galactic plane)
Right ascension of North pole[17]	286.13° 19 h 4 min 30 s
Declination of North pole	+63.87° 63° 52' North
Sidereal rotation period	25.05 days at equator 25.38 days at 16° latitude 34.4 days at poles[5]
Rotation velocity (at equator)	1.997 km/s[12]

Speed of light

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"Lightspeed" redirects here. For other uses, see Speed of light (disambiguation) and Lightspeed (disambiguation).

Speed of light

On average, sunlight takes about 8 minutes and 17 seconds to travel from the Sun to Earth.
Exact values
metres per second	299792458
Approximate values (to three significant digits)
kilometres per hour	1080000000
miles per second	186000
miles per hour[1]	671000000
astronomical units per day	173[Note 1]
parsecs per year	0.307[Note 2]
Approximate light signal travel times
Distance	Time
one foot	1.0 ns
one metre	3.3 ns
from geostationary orbit to Earth	119 ms
the length of Earth's equator	134 ms
from Moon to Earth	1.3 s
from Sun to Earth (1 AU)	8.3 min
one light-year	1.0 year
one parsec	3.26 years
from the nearest star to Sun (1.3 pc)	4.2 years
from the nearest galaxy to Earth	25000 years
across the Milky Way	100000 years
from the Andromeda Galaxy to Earth	2.5 million years

Special relativity
Principle of relativity Theory of relativity
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The speed of light in vacuum, commonly denoted c, is a universal physical constant that is important in many areas of physics. The speed of light c is exactly equal to 299,792,458 metres per second (approximately 300,000 kilometres per second; 186,000 miles per second; 671 million miles per hour).^{[Note 3]} According to the special theory of relativity, c is the upper limit for the speed at which conventional matter or energy (and thus any signal carrying information) can travel through space.^[4][5][6]

All forms of electromagnetic radiation, including visible light, travel at the speed of light. For many practical purposes, light and other electromagnetic waves will appear to propagate instantaneously, but for long distances and very sensitive measurements, their finite speed has noticeable effects. Starlight viewed on Earth left the stars many years ago, allowing humans to study the history of the universe by viewing distant objects. When communicating with distant space probes, it can take minutes to hours for signals to travel from Earth to the spacecraft and vice versa. In computing, the speed of light fixes the ultimate minimum communication delay between computers, to computer memory, and within a CPU. The speed of light can be used in time of flight measurements to measure large distances to extremely high precision.

Ole Rømer first demonstrated in 1676 that light travels at a finite speed (non-instantaneously) by studying the apparent motion of Jupiter's moon Io. Progressively more accurate measurements of its speed came over the following centuries. In a paper published in 1865, James Clerk Maxwell proposed that light was an electromagnetic wave and, therefore, travelled at speed c.^[7] In 1905, Albert Einstein postulated that the speed of light c with respect to any inertial frame of reference is a constant and is independent of the motion of the light source.^[8] He explored the consequences of that postulate by deriving the theory of relativity and, in doing so, showed that the parameter c had relevance outside of the context of light and electromagnetism.

Massless particles and field perturbations, such as gravitational waves, also travel at speed c in a vacuum. Such particles and waves travel at c regardless of the motion of the source or the inertial reference frame of the observer. Particles with nonzero rest mass can be accelerated to approach c but can never reach it, regardless of the frame of reference in which their speed is measured. In the special and general theories of relativity, c interrelates space and time and also appears in the famous equation of mass–energy equivalence, E = mc².^[9]

In some cases, objects or waves may appear to travel faster than light (e.g., phase velocities of waves, the appearance of certain high-speed astronomical objects, and particular quantum effects). The expansion of the universe is understood to exceed the speed of light beyond a certain boundary.

The speed at which light propagates through transparent materials, such as glass or air, is less than c; similarly, the speed of electromagnetic waves in wire cables is slower than c. The ratio between c and the speed v at which light travels in a material is called the refractive index n of the material (n = c/v). For example, for visible light, the refractive index of glass is typically around 1.5, meaning that light in glass travels at c/1.5 ≈ 200000 km/s (124000 mi/s); the refractive index of air for visible light is about 1.0003, so the speed of light in air is about 90 km/s (56 mi/s) slower than c.

Contents

• 1Numerical value, notation, and units
  • 1.1Use in unit systems
• 2Fundamental role in physics
  • 2.1Upper limit on speeds
• 3Faster-than-light observations and experiments
• 4Propagation of light
  • 4.1In a medium
• 5Practical effects of finiteness
  • 5.1Small scales
  • 5.2Large distances on Earth
  • 5.3Spaceflight and astronomy
  • 5.4Distance measurement
• 6Measurement
  • 6.1Astronomical measurements
  • 6.2Time of flight techniques
  • 6.3Electromagnetic constants
  • 6.4Cavity resonance
  • 6.5Interferometry
• 7History
  • 7.1Early history
  • 7.2First measurement attempts
  • 7.3Connections with electromagnetism
  • 7.4"Luminiferous aether"
  • 7.5Special relativity
  • 7.6Increased accuracy of c and redefinition of the metre and second
  • 7.7Defined as an explicit constant
• 8See also
• 9Notes
• 10References
• 11Further reading
  • 11.1Historical references
  • 11.2Modern references
• 12
  
  
  External links
  
  Moon 
  The near side of the Moon (north at top) as seen from Earth
  Designations
  Designation
  Earth I
  Alternative names
  • Luna
  • Selene (poetic)
  • Cynthia (poetic)
  Adjectives
  • Lunar
  • Selenian (poetic)
  • Cynthian (poetic)
  • Moonly (poetic)
  Orbital characteristicsEpoch J2000Perigee362600 km
  (356400–370400 km)Apogee405400 km
  (404000–406700 km)
  Semi-major axis
  384399 km  (1.28 ls, 0.00257 AU)^[1]Eccentricity0.0549^[1]
  Orbital period (sidereal)
  27.321661 d
  (27 d 7 h 43 min 11.5 s^[1])
  Orbital period (synodic)
  29.530589 d
  (29 d 12 h 44 min 2.9 s)
  Average orbital speed
  1.022 km/sInclination5.145° to the ecliptic^[2][a]
  Longitude of ascending node
  Regressing by one revolution in 18.61 years
  Argument of perigee
  Progressing by one
  revolution in 8.85 years
  Satellite ofEarth^[b][3]Physical characteristics
  Mean radius
  1737.4 km  
  (0.2727 of Earth's)^[1][4][5]
  Equatorial radius
  1738.1 km  
  (0.2725 of Earth's)^[4]
  Polar radius
  1736.0 km  
  (0.2731 of Earth's)^[4]Flattening0.0012^[4]Circumference10921 km  (equatorial)
  Surface area
  3.793×10⁷ km²  
  (0.074 of Earth's)Volume2.1958×10¹⁰ km³  
  (0.02 of Earth's)^[4]Mass7.342×10²² kg  
  (0.0123 of Earth's)^[1][4][6]
  Mean density
  3.344 g/cm^3[1][4]
  0.606 × Earth
  Surface gravity
  1.622 m/s²  (0.1654 g; 5.318 ft/s²)^[4]
  Moment of inertia factor
  0.3929±0.0009^[7]
  Escape velocity
  2.38 km/s
  (8600 km/h; 5300 mph)
  Synodic rotation period
  29.530589 d
  (29 d 12 h 44 min 2.9 s; synodic; solar day) (spin-orbit locked)
  Sidereal rotation period
  27.321661 d  (spin-orbit locked)
  Equatorial rotation velocity
  4.627 m/s
  Axial tilt
  • 1.5424° to ecliptic^[8]
  • 6.687° to orbit plane^[2]
  • 24° to Earth's equator ^[9]
  North pole right ascension
  • 17^h 47^m 26^s
  • 266.86°^[10]
  North pole declination
  65.64°^[10]Albedo0.136^[11]

  Surface temp.	min	mean	max
  Equator	100 K[12]	250 K	390 K[12]
  85°N		150 K	230 K[13]

  Surface absorbed dose rate13.2 μGy/h^[14]Surface equivalent dose rate57.0 μSv/h^[14]
  Apparent magnitude
  • −2.5 to −12.9^[c]
  • −12.74  (mean full moon)^[4]
  Angular diameter
  29.3 to 34.1 arcminutes^[4][d]Atmosphere^[15]
  Surface pressure
  • 10⁻⁷ Pa (1 picobar)  (day)
  • 10⁻¹⁰ Pa (1 femtobar)   
    (night)^[e]
  Composition by volume
  • He
  • Ar
  • Ne
  • Na
  • K
  • H
  • Rn
  • 
    

  • Mercury 

    Mercury in true color (by MESSENGER in 2008)
    Designations
    Pronunciation	/ˈmɜːrkjʊri/ (listen)
    Adjectives	Mercurian /mərˈkjʊəriən/,[1] Mercurial /mərˈkjʊəriəl/[2]
    Orbital characteristics[5]
    Epoch J2000
    Aphelion	0.466697 AU 69,816,900 km
    Perihelion	0.307499 AU 46,001,200 km
    Semi-major axis	0.387098 AU 57,909,050 km
    Eccentricity	0.205630[3]
    Orbital period (sidereal)	87.9691 d 0.240846 yr 0.5 Mercury synodic day
    Orbital period (synodic)	115.88 d[3]
    Average orbital speed	47.36 km/s[3]
    Mean anomaly	174.796°
    Inclination	7.005° to ecliptic 3.38° to Sun's equator 6.35° to invariable plane[4]
    Longitude of ascending node	48.331°
    Argument of perihelion	29.124°
    Satellites	None
    Physical characteristics
    Mean diameter	4880 km
    Mean radius	2,439.7±1.0 km[6][7] 0.3829 Earths
    Flattening	0.0009[3]
    Surface area	7.48×107 km2[6] 0.147 Earths
    Volume	6.083×1010 km3[6] 0.056 Earths
    Mass	3.3011×1023 kg[8] 0.055 Earths
    Mean density	5.427 g/cm3[6]
    Surface gravity	3.7 m/s2 0.38 g[6]
    Moment of inertia factor	0.346±0.014[9]
    Escape velocity	4.25 km/s[6]
    Synodic rotation period	176 d[10]
    Sidereal rotation period	58.646 d 1407.5 h[6]
    Equatorial rotation velocity	10.892 km/h (3.026 m/s)
    Axial tilt	2.04′ ± 0.08′ (to orbit)[9] (0.034°)[3]
    North pole right ascension	18h 44m 2s 281.01°[3]
    North pole declination	61.45°[3]
    Albedo	0.088 (Bond)[11] 0.142 (geom.)[12]
    Surface temp. min mean max 0°N, 0°W [13] -173 °C 67 °C 427 °C 85°N, 0°W[13] -193 °C -73 °C 106.85 °C
    Apparent magnitude	−2.48 to +7.25[14]
    Angular diameter	4.5–13″[3]
    Atmosphere[3][15][16]
    Surface pressure	trace (≲ 0.5 nPa)
    Composition by volume	atomic oxygen sodium magnesium atomic hydrogen potassium calcium helium Trace amounts of iron, aluminium, argon, dinitrogen, dioxygen, carbon dioxide, water vapor, xenon, krypton, and neon

    Mercury is the smallest planet in the Solar System and the closest to the Sun. Its orbit around the Sun takes 87.97 Earth days, the shortest of all the Sun's planets. It is named after the Roman god Mercurius (Mercury), god of commerce, messenger of the gods, and mediator between gods and mortals, corresponding to the Greek god Hermes (Ἑρμῆς). Like Venus, Mercury orbits the Sun within Earth's orbit as an inferior planet, and its apparent distance from the Sun as viewed from Earth never exceeds 28°. This proximity to the Sun means the planet can only be seen near the western horizon after sunset or the eastern horizon before sunrise, usually in twilight. At this time, it may appear as a bright star-like object, but is more difficult to observe than Venus. From Earth, the planet telescopically displays the complete range of phases, similar to Venus and the Moon, which recurs over its synodic period of approximately 116 days.

    Mercury rotates in a way that is unique in the Solar System. It is tidally locked with the Sun in a 3:2 spin–orbit resonance,^[17] meaning that relative to the fixed stars, it rotates on its axis exactly three times for every two revolutions it makes around the Sun.^[a][18] As seen from the Sun, in a frame of reference that rotates with the orbital motion, it appears to rotate only once every two Mercurian years. An observer on Mercury would therefore see only one day every two Mercurian years.

    Mercury's axis has the smallest tilt of any of the Solar System's planets (about 1⁄30 degree). Its orbital eccentricity is the largest of all known planets in the Solar System;^[b] at perihelion, Mercury's distance from the Sun is only about two-thirds (or 66%) of its distance at aphelion. Mercury's surface appears heavily cratered and is similar in appearance to the Moon's, indicating that it has been geologically inactive for billions of years. Having almost no atmosphere to retain heat, it has surface temperatures that vary diurnally more than on any other planet in the Solar System, ranging from 100 K (−173 °C; −280 °F) at night to 700 K (427 °C; 800 °F) during the day across the equatorial regions.^[19] The polar regions are constantly below 180 K (−93 °C; −136 °F). The planet has no known natural satellites.

    Two spacecraft have visited Mercury: Mariner 10 flew by in 1974 and 1975; and MESSENGER, launched in 2004, orbited Mercury over 4,000 times in four years before exhausting its fuel and crashing into the planet's surface on April 30, 2015.^[20][21][22] The BepiColombo spacecraft is planned to arrive at Mercury in 2025.

    Contents

    • 1Nomenclature
    • 2Physical characteristics
      • 2.1Internal structure
      • 2.2Surface geology
        • 2.2.1Impact basins and craters
        • 2.2.2Plains
        • 2.2.3Compressional features
        • 2.2.4Volcanism
      • 2.3Surface conditions and exosphere
      • 2.4Magnetic field and magnetosphere
    • 3Orbit, rotation, and longitude
      • 3.1Longitude convention
      • 3.2Spin-orbit resonance
      • 3.3Advance of perihelion
    • 4Observation
    • 5Observation history
      • 5.1Ancient astronomers
      • 5.2Ground-based telescopic research
      • 5.3Research with space probes
        • 5.3.1Mariner 10
        • 5.3.2MESSENGER
        • 5.3.3BepiColombo
    • 6See also
    • 7Notes
    • 8References
    • 9External links

    Nomenclature

    The ancients knew Mercury by different names depending on whether it was an evening star or a morning star. By about 350 BC, the ancient Greeks had realized the two stars were one.^[23] They knew the planet as Στίλβων Stilbōn, meaning "twinkling", and Ἑρμής Hermēs, for its fleeting motion,^[24] a name that is retained in modern Greek (Ερμής Ermis).^[25] The Romans named the planet after the swift-footed Roman messenger god, Mercury (Latin Mercurius), which they equated with the Greek Hermes, because it moves across the sky faster than any other planet.^[23][26] The astronomical symbol for Mercury is a stylized version of Hermes' caduceus; a Christian cross was added in the 16th century: .^[27][28]

    Physical characteristics

    Mercury is one of four terrestrial planets in the Solar System, and is a rocky body like Earth. It is the smallest planet in the Solar System, with an equatorial radius of 2,439.7 kilometres (1,516.0 mi).^[3] Mercury is also smaller—albeit more massive—than the largest natural satellites in the Solar System, Ganymede and Titan. Mercury consists of approximately 70% metallic and 30% silicate material.^[29]

    Internal structure

    

    Mercury's internal structure and magnetic field

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  Saturn 

  Pictured in natural color approaching equinox, photographed by Cassini in July 2008; the dot in the bottom left corner is Titan

  DesignationsPronunciation/ˈsætərn/ (listen)^[1]

  Named after

  SaturnAdjectivesSaturnian /səˈtɜːrniən/,^[2] Cronian^[3] / Kronian^[4] /ˈkroʊniən/^[5]Orbital characteristics^[11]Epoch J2000.0Aphelion1,514.50 million km (10.1238 AU)Perihelion1,352.55 million km (9.0412 AU)

  Semi-major axis

  1,433.53 million km (9.5826 AU)Eccentricity0.0565

  Orbital period (sidereal)

  • 29.4571 yr
  • 10,759.22 d
  • 24,491.07 Saturnian solar days^[6]

  Orbital period (synodic)

  378.09 days

  Average orbital speed

  9.68 km/s (6.01 mi/s)

  Mean anomaly

  317.020°^[7]Inclination

  • 2.485° to ecliptic^[7]
  • 5.51° to Sun's equator^[7]
  • 0.93° to invariable plane^[8]

  Longitude of ascending node

  113.665°

  Time of perihelion

  2032-Nov-29^[9]

  Argument of perihelion

  339.392°^[7]Known satellites83 with formal designations; innumerable additional moonlets.^[10]Physical characteristics^[11]

  Mean radius

  58,232 km (36,184 mi)^[a]
  9.1402 Earths

  Equatorial radius

  • 60,268 km (37,449 mi)^[a]
  • 9.449 Earths

  Polar radius

  • 54,364 km (33,780 mi)^[a]
  • 8.552 Earths

  Flattening0.09796Circumference

  • 365882.4 km equatorial (227348.8 mi)^[12]

  Surface area

  • 4.27×10¹⁰ km² (1.65×10¹⁰ sq mi)^[13][a]
  • 83.703 Earths

  Volume

  • 8.2713×10¹⁴ km³ (1.9844×10¹⁴ cu mi)^[a]
  • 763.59 Earths

  Mass

  • 5.6834×10²⁶ kg
  • 95.159 Earths

  Mean density

  0.687 g/cm³ (0.0248 lb/cu in)^[b] (less than water)
  0.1246 Earths

  Surface gravity

  • 10.44 m/s² (34.3 ft/s²)^[a]
  • 1.065 g

  Moment of inertia factor

  0.22^[14]

  Escape velocity

  35.5 km/s (22.1 mi/s)^[a]

  Synodic rotation period

  10 h 32 m 36 s;
  10.5433 hours^[6]

  Sidereal rotation period

  10^h 33^m 38^s + 1^m 52^s
  − 1^m 19^s [15][16]

  Equatorial rotation velocity

  9.87 km/s (6.13 mi/s; 35,500 km/h)^[a]

  Axial tilt

  26.73° (to orbit)

  North pole right ascension

  40.589°; 2^h 42^m 21^s

  North pole declination

  83.537°Albedo

  • 0.342 (Bond)^[17]
  • 0.499 (geometric)^[18]

  Surface temp.	min	mean	max
  1 bar		134 K
  0.1 bar	88 K[20]	97 K[21]	151 K[20]

  Apparent magnitude

  −0.55^[19] to +1.17^[19]

  Angular diameter

  14.5″ to 20.1″ (excludes rings)Atmosphere^[11]

  Surface pressure

  140 kPa^[22]

  Scale height

  59.5 km (37.0 mi)Composition by volume

  • 96.3%±2.4% hydrogen
  • 3.25%±2.4% helium
  • 0.45%±0.2% methane
  • 0.0125%±0.0075% ammonia
  • 0.0110%±0.0058% hydrogen deuteride
  • 0.0007%±0.00015% ethane
  • Icy volatiles: 
    • ammonia
    • water ice
    • ammonium hydrosulfide

    • Uranus  ()

      Photograph of Uranus in true colour (by Voyager 2 in 1986)
      Discovery
      Discovered by	William Herschel
      Discovery date	13 March 1781
      Designations
      Pronunciation	/ˈjʊərənəs/ (listen)[1] or /jʊˈreɪnəs/ (listen)[2]
      Named after	the Latin form Ūranus of the Greek god Οὐρανός Ouranos
      Adjectives	Uranian (/jʊˈreɪniən/)[3]
      Orbital characteristics[10][a]
      Epoch J2000
      Aphelion	20.0965 AU (3006.39 Gm)
      Perihelion	18.2861 AU (2735.56 Gm)
      Semi-major axis	19.19126 AU (2870.972 Gm)
      Eccentricity	0.04717
      Orbital period (sidereal)	84.0205 yr 30,688.5 d[4] 42,718 Uranian solar days[5]
      Orbital period (synodic)	369.66 days[6]
      Average orbital speed	6.80 km/s[6]
      Mean anomaly	142.238600°
      Inclination	0.773° to ecliptic 6.48° to Sun's equator 0.99° to invariable plane[7]
      Longitude of ascending node	74.006°
      Time of perihelion	17–19 August 2050[8][9]
      Argument of perihelion	96.998857°
      Known satellites	27
      Physical characteristics
      Mean radius	25,362±7 km[11][b]
      Equatorial radius	25,559±4 km 4.007 Earths[11][b]
      Polar radius	24,973±20 km 3.929 Earths[11][b]
      Flattening	0.0229±0.0008[c]
      Circumference	159,354.1 km[4]
      Surface area	8.1156×109 km2[4][b] 15.91 Earths
      Volume	6.833×1013 km3[6][b] 63.086 Earths
      Mass	(8.6810±0.0013)×1025 kg 14.536 Earths[12] GM=5,793,939±13 km3/s2
      Mean density	1.27 g/cm3[6][d]
      Surface gravity	8.69 m/s2[6][b] 0.886 g
      Moment of inertia factor	0.23[13] (estimate)
      Escape velocity	21.3 km/s[6][b]
      Synodic rotation period	−0.71832 d −17 h 14 m 23 s (retrograde)[5]
      Sidereal rotation period	−0.71833 d −17 h 14 min 24 s (retrograde)[11]
      Equatorial rotation velocity	2.59 km/s 9,320 km/h
      Axial tilt	97.77° (to orbit)[6]
      North pole right ascension	17h 9m 15s 257.311°[11]
      North pole declination	−15.175°[11]
      Albedo	0.300 (Bond)[14] 0.488 (geom.)[15]
      Surface temp. min mean max 1 bar level[16] 76 K (−197.2 °C) 0.1 bar (tropopause)[17] 47 K 53 K 57 K
      Apparent magnitude	5.38[18] to 6.03[18]
      Angular diameter	3.3″ to 4.1″[6]
      Atmosphere[17][19][20][e]
      Scale height	27.7 km[6]
      Composition by volume	Below 1.3 bar (130 kPa): 83 ± 3% hydrogen 15 ± 3% helium 2.3% methane 0.009% (0.007–0.015%) hydrogen deuteride hydrogen sulfide (trace amount) Icy volatiles:  ammonia water ice ammonium hydrosulfide methane hydrate