ESA Science & Technology: Uranus

Uranus

Origin of name
Uranus is named after the father of Saturn in Roman mythology.

Discovered by
William Herschel in 1781

Satellites
Named after characters from Shakespeare's plays and from Pope's "Rape of the Lock".

Property	Unit	Value	Earth = 1
Equatorial radius, 1 bar level	km	25 559	4.007
Polar radius, 1 bar level	km	24 973	3.929
Flattening		0.02293	6.84
Mass (x10²⁴)	kg	86.832	14.536
Volume (x10¹⁰)	km³	6833	63.08
Mean density	kgm^-3	1270	0.230
Gravity at equator, 1 bar level	ms^-2	8.87	0.905
Escape velocity	kms^-1	21.3	1.903
Magnetic field at equator (x10^-4)	T	0.23	0.75
Magnetic dipole moment (x10¹⁷)	Tm³	~ 3.9	~ 50
Tilt of dipole axis	°	58.6
Dipole field centre offset from planet centre (equatorial radii)		0.3
Number of natural satellites		27

Property	Unit	Value
Perihelion (x10⁶)	km	2741.30
Aphelion (x10⁶)	km	3003.62
Mean distance from the Sun (x10⁶)	km	2869.6
Mean distance from the Sun	AU	19.182
Eccentricity		0.0457
Sidereal orbit period	y	84.01
Sidereal rotation period Magnetic coordinates (Voyager 2)	h	R 17.24
Length of day	h	17.24
Orbit inclination to Ecliptic	°	0.77
Mean orbital velocity	kms^-1	6.81
Maximum orbital velocity	kms^-1	7.11
Minimum orbital velocity	kms^-1	6.49
Axial tilt	°	97.77

Sidereal orbit period
The time taken by the planet to complete exactly one orbit around the Sun with respect to the celestial sphere.
Sidereal rotation period
The time in which the planet rotates around its axis exactly 360° with respect to the celestial sphere.
Length of a day
Defined as the time between two successive sunrises over the meridian.
Magnetic dipole moment
Calculated as the ratio of the magnetic field strength at the equator divided by the cube of the equatorial radius.

Last Update: 14 May 2013