The Jovian Planets, Part IIIThe Jovian Planets, Part III
Uranus and NeptuneUranus and Neptune
URANUSURANUSThe God of the HeavensThe God of the Heavens
Physical DataPhysical Data
Discovered by William Herschel in 1781Discovered by William Herschel in 1781 Diameter: 51,118 km (4.01 DDiameter: 51,118 km (4.01 Dearthearth))
Mass: 8.69x10Mass: 8.69x102525 kg (14.54 M kg (14.54 Mearthearth))
Density: 1.24 g/cmDensity: 1.24 g/cm33
Rotation Period: 17.24 hoursRotation Period: 17.24 hours Tilt of Axis: 98Tilt of Axis: 98oo (retrograde rotation!) (retrograde rotation!) Surface Temperature: 52 K (-366Surface Temperature: 52 K (-366oo F) F)
Physical DataPhysical Data
Orbital Semi-Major Axis: 19.18 AUOrbital Semi-Major Axis: 19.18 AU Orbital Period: 84.01 yearsOrbital Period: 84.01 years Orbital Inclination: 0.8Orbital Inclination: 0.8oo
Orbital Eccentricity: 0.047Orbital Eccentricity: 0.047 Surface Gravity: 0.919 Earth gravitySurface Gravity: 0.919 Earth gravity Satellites: 27 as of 2011Satellites: 27 as of 2011 Magnetic Field: yesMagnetic Field: yes
Uranus’ InteriorUranus’ Interior
ATMOSPHEREMOLECULAR HYDROGEN
ICE
ROCK
The Discovery of UranusThe Discovery of Uranus
First discovered planet First discovered planet even though at its even though at its closest to earth it can be closest to earth it can be seen with the naked eyeseen with the naked eye
Was recorded 22 times Was recorded 22 times as a star on star charts as a star on star charts before W. Herschel before W. Herschel discovered it as a planet discovered it as a planet in 1781in 1781
m
Uranus’ MotionsUranus’ Motions
N
N
N
N
S
S
S
S
SUN
Uranus rotates on its side, producing strangeseasons and day-night patterns
Uranus’ AtmosphereUranus’ Atmosphere
COMPOSITION:COMPOSITION: 85% Hydrogen85% Hydrogen 15% Helium15% Helium Traces of MethaneTraces of Methane
CLOUDS:CLOUDS: Mostly made of methane iceMostly made of methane ice Featureless cloudtops (inconspicous bands)Featureless cloudtops (inconspicous bands)
Uranus’ Magnetic FieldUranus’ Magnetic Field
Magnetic dipole is Magnetic dipole is offset 31% from the offset 31% from the center of the planetcenter of the planet
Tilted -59Tilted -59oo from from rotational axisrotational axis
Comparable in strength Comparable in strength to Earth’s (0.74 Earth’s)to Earth’s (0.74 Earth’s)
Uranus has aurora and Uranus has aurora and radio emissionsradio emissions
Uranus’ RingsUranus’ Rings
Found from star Found from star occultations in 1977occultations in 1977
Thought to be made Thought to be made of stoneof stone
Uranus also has Uranus also has partial rings called partial rings called “ring arcs”“ring arcs”
Also has sheperd Also has sheperd satellitessatellites
Uranus’ MoonsUranus’ Moons
All are named after William Shakespeare All are named after William Shakespeare and Alexander Pope charactersand Alexander Pope characters
There are 15 known moonsThere are 15 known moons
Uranus’ MoonsUranus’ Moons
MIRANDA:MIRANDA: Surface is a weird mix of Surface is a weird mix of
old and new terrainold and new terrain It has been proposed It has been proposed
than it was shattered and than it was shattered and reassembled in this wayreassembled in this way
There was not enough There was not enough heat to fuse it smoothly heat to fuse it smoothly togethertogether
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Uranus’ MoonsUranus’ Moons
ARIEL:ARIEL: Youngest surface of Youngest surface of
the Uranian Satellitesthe Uranian Satellites There is evidence of There is evidence of
tectonic activitytectonic activity It has faults over 10 It has faults over 10
km deepkm deep
Uranus’ MoonsUranus’ Moons
TITANIA:TITANIA: Largest of Uranus’ Largest of Uranus’
moonsmoons Has faults up to 100 Has faults up to 100
km acrosskm across Has a heavily cratered Has a heavily cratered
surfacesurface
NEPTUNENEPTUNEGOD OF THE SEAGOD OF THE SEA
Physical DataPhysical Data
First observed in 1846 by Johann GalleFirst observed in 1846 by Johann Galle Diameter: 49,500 km (3.89 DDiameter: 49,500 km (3.89 Dearthearth))
Mass: 1.030x10Mass: 1.030x102626 kg (17.23 M kg (17.23 Mearthearth) )
Density: 1.61 g/cmDensity: 1.61 g/cm33
Rotation Period: 16.11 hoursRotation Period: 16.11 hours Tilt of Axis: 28.76Tilt of Axis: 28.76oo
Surface Temperature: 57 K (-357Surface Temperature: 57 K (-357oo F) F)
Physical DataPhysical Data
Orbital Semi-Major Axis: 30.06 AUOrbital Semi-Major Axis: 30.06 AU Orbital Period: 164.79 yearsOrbital Period: 164.79 years Orbital Inclination: 1.8Orbital Inclination: 1.8oo
Orbital Eccentricity: 0.009Orbital Eccentricity: 0.009 Surface Gravity: 1.19 Earth’s gravitySurface Gravity: 1.19 Earth’s gravity Satellites: 13 as of 2011Satellites: 13 as of 2011 Magnetic Field: yesMagnetic Field: yes
The Discovery of NeptuneThe Discovery of Neptune
It’s existence was calculated before it was It’s existence was calculated before it was observed from variations of Uranus’ orbit from observed from variations of Uranus’ orbit from what was predictedwhat was predicted
Calculations were made by U.J. Leverrier, sent to Calculations were made by U.J. Leverrier, sent to Johann Galle at Berlin Observatory, and he found Johann Galle at Berlin Observatory, and he found Neptune after searching for 30 minutesNeptune after searching for 30 minutes
Galileo actually recorded Neptune twice in 1612 Galileo actually recorded Neptune twice in 1612 and 1613 in his notebooks as a background star in and 1613 in his notebooks as a background star in his drawings of Jupiterhis drawings of Jupiter
Neptune’s InteriorNeptune’s Interior
ATMOSPHERE
MOLECULAR HYDROGEN
ICE
ROCK
Similar to Uranus
Neptune’s AtmosphereNeptune’s Atmosphere
75% Hydrogen75% Hydrogen 25% Helium25% Helium Small amounts of: Methane, Ammonia &Small amounts of: Methane, Ammonia &
AcetyleneAcetylene
There are three majors cloud-top features:There are three majors cloud-top features:The Great Dark SpotThe Great Dark SpotDark Spot 2Dark Spot 2ScooterScooter
Neptune’s AtmosphereNeptune’s Atmosphere
The Great Dark Spot:The Great Dark Spot: Anti-cyclone with a Anti-cyclone with a
circulation period of circulation period of 16 days16 days
About the size of About the size of EarthEarth
In southern In southern hemispherehemisphere
Neptune’s AtmosphereNeptune’s Atmosphere
Dark Spot 2:Dark Spot 2: Smaller cyclone in S. Smaller cyclone in S.
hemisperehemispere
Scooter:Scooter: Fast rotatingFast rotating Rapidly changes shape Rapidly changes shape
Great Dark Spot
Scooter
Dark Spot 2
Neptune’s Magnetic FieldNeptune’s Magnetic Field
Magnetic dipole is Magnetic dipole is offset 55% from center offset 55% from center of Neptuneof Neptune
Tilted -47Tilted -47oo with with respect to rotational respect to rotational axisaxis
Has a field strength of Has a field strength of 0.4x Earth’s at the 0.4x Earth’s at the equatorequator
Has aurora and radio Has aurora and radio emissionsemissions
Neptune’s RingsNeptune’s Rings
Discovered in 1981Discovered in 1981 Brighter areas are ring Brighter areas are ring
arcsarcs There is a total of 5 There is a total of 5
rings, all very thinrings, all very thin
Neptune’s MoonsNeptune’s Moons
TRITON:TRITON: Has thin atmosphere, Has thin atmosphere,
geysers, and strange geysers, and strange “cantaloupe terrain”“cantaloupe terrain”
Diameter: 3000kmDiameter: 3000km
Neptune’s MoonsNeptune’s Moons
Proteus:Proteus: Second largest moon Second largest moon
of Neptune discovered of Neptune discovered by Voyagerby Voyager
Surprisingly, Neried, Surprisingly, Neried, Neptune’s third largest Neptune’s third largest moon was discovered moon was discovered from the ground from the ground before Proteusbefore Proteus