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1. This article is about the planet. For other uses, see Uranus (disambiguation).
Tests test
Deeded
Uranus presented a nearly featureless disk to Voyager 2
Discovery
Discovered by William Herschel
Discovery date March 13, 1781
Designations
Pronunciation i /ˈjʊərənəs/ or i /jʊˈreɪnəs/[1][2]
Adjective Uranian
Orbital characteristics[3][a]
Epoch J2000
Aphelion 3,004,419,704 km
20.083 305 26 AU
Perihelion 2,748,938,461 km
18.375 518 63 AU
Semi-major axis 2,876,679,082 km
19.229 411 95 AU
Eccentricity 0.044 405 586
Orbital period 30,799.095 days
84.323 326 yr
42,718 Uranus solar days[4]
Synodic period 369.66 days[5]
Average orbital speed 6.81 km/s[5]
Mean anomaly142.955 717°
Inclination 0.772 556° to Ecliptic
6.48° to Sun's equator
1.02° to Invariable plane[6]
Longitude of ascending node 73.989 821°
Argument of perihelion 96.541 318°
Satellites 27
Physical characteristics
Equatorial radius 25,559 ± 4 km
4.007 Earths[7][c]
Polar radius 24,973 ± 20 km
3.929 Earths[7][c]
Flattening 0.022 9 ± 0.000 8[b]
Circumference156,909.98 km[citation needed]
Surface area 8.115 6×109 km2[8][c]
15.91 Earths
Volume 6.833×1013 km3[5][c]
63.086 Earths
Mass (8.6810 ± 0.0013)×1025 kg
14.536 Earths[9]
GM=5 793 939 ± 13 km3/s2
Mean density 1.27 g/cm3[5][c]
Equatorial surface gravity 8.69 m/s2[5][c]
0.886 g

2. Escape velocity 21.3 km/s[5][c]
Sidereal rotation
period –0.718 33 day
17 h 14 min 24 s[7]
Equatorial rotation velocity 2.59 km/s
9,320 km/h
Axial tilt 97.77°[7]
North pole right ascension 17 h 9 min 15 s
257.311°[7]
North pole declination–15.175°[7]
Albedo0.300 (Bond)
0.51 (geom.)[5]
Surface temp.
1 bar level[11]
0.1 bar
(tropopause)[12]
min mean max
76 K
49 K 53 K 57 K
Apparent magnitude 5.9[10] to 5.32[5]
Angular diameter 3.3"–4.1"[5]
Atmosphere[12][13][14][d]
Scale height 27.7 km[5]
Composition (Below 1.3 bar)
83 ± 3% Hydrogen (H2)
15 ± 3% Helium
2.3% Methane
0.009%
(0.007–0.015%) Hydrogen deuteride (HD)[15]
Ices:
Ammonia
water
ammonium hydrosulfide (NH4SH)
methane (CH4)
Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest
planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus
(Ancient Greek: Οὐρανός), the father of Cronus (Saturn) and grandfather of Zeus (Jupiter). Though it
is visible to the naked eye like the five classical planets, it was never recognized as a planet by ancient
observers because of its dimness and slow orbit.[16] Sir William Herschel announced its discovery on
March 13, 1781, expanding the known boundaries of the Solar System for the first time in modern
history. Uranus was also the first planet discovered with a telescope.
Uranus is similar in composition to Neptune, and both are of different chemical composition than the
larger gas giants Jupiter and Saturn. As such, astronomers sometimes place them in a separate category,
the "ice giants". Uranus's atmosphere, while similar to Jupiter and Saturn's in its primary composition
of hydrogen and helium, contains more "ices" such as water, ammonia and methane, along with traces
of hydrocarbons.[12] It is the coldest planetary atmosphere in the Solar System, with a minimum
temperature of 49 K (–224 °C). It has a complex, layered cloud structure, with water thought to make
up the lowest clouds, and methane thought to make up the uppermost layer of clouds.[12] In contrast,
the interior of Uranus is mainly composed of ices and rock.[11]

3. Like the other giant planets, Uranus has a ring system, a magnetosphere, and numerous moons. The
Uranian system has a unique configuration among the planets because its axis of rotation is tilted
sideways, nearly into the plane of its revolution about the Sun. As such, its north and south poles lie
where most other planets have their equators.[17] Seen from Earth, Uranus's rings can sometimes
appear to circle the planet like an archery target and its moons revolve around it like the hands of a
clock, though in 2007 and 2008 the rings appeared edge-on. In 1986, images from Voyager 2 showed
Uranus as a virtually featureless planet in visible light without the cloud bands or storms associated
with the other giants.[17] Terrestrial observers have seen signs of seasonal change and increased
weather activity in recent years as Uranus approached its equinox. The wind speeds on Uranus can
reach 250 meters per second (900 km/h, 560 mph).[18]