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Universe 1
Astronomy 20 1
Uranus & Neptune
The water planets
Astronomy 20 2
Uranian planets
The Uranian Planets
4x Earth diameter Bluish green H atmospheres Methane gives blue tint Uranus 3rd largest in size Neptune 3rd largest in mass Watery interiors
Watery "slush"
Rocky core
Astronomy 20 3
Uranian planets
Uranus discovery
William Herschel, 1781 First planet discovered
telescopically 20 AU from Sun – doubled
size of Solar System
Saturn
Uranus
Universe 2
Astronomy 20 4
Uranian planets
UranusPre-Voyager discoveries
Orbital period 84 years 5 medium-sized moons Axis tilted 90º Rings detected 1977 by stellar
occultation
Gerard Kuiper
Astronomy 20 5
Uranian planets
Uranus seasons
Astronomy 20 6
Uranian planets
UranusVoyager 2 encounter
January 1986 Solstice Bull’s eye
Universe 3
Astronomy 20 7
Uranian planets
UranusAtmosphere
Nearly featureless fuzzball. A few clouds of methane ice East-west winds Temperature the same on day
side as night side.
Astronomy 20 8
Uranian planets
UranusOther Voyager 2 results
10 new small inner moons 2 innermost: shepherd moons
Close-ups of rings Bizarre magnetic field
tilted 60º offset 1/3 toward surface Rotation period: 17 hr
Shepherd moons
Astronomy 20 9
Uranian planets
Uranus rings
Universe 4
Astronomy 20 13
Uranian planets
Discovery of Neptune1846
Uranus deviates Unseen gravitational source Jean Joseph LeVerrier John Couch Adams Johann Gottfried Galle, Berlin
Observatory
Astronomy 20 14
Uranian planets
Neptune Pre-Voyager discoveries
Moons Triton (retrograde) Nereid (eccentric)
Rotation: 16 hours “Ring arcs”
Astronomy 20 15
Uranian planets
NeptuneVoyager 2 encounter
August 1989 Close pass over north pole Triton last encounter
Universe 5
Astronomy 20 16
Uranian planets
Voyager at NeptuneAtmosphere
Great Dark Spot Methane ice clouds Fastest winds: >1200 km/hr Mysterious underlying cloud deck
Great Dark Spot
Lesser Dark Spot
Astronomy 20 17
Uranian planets
The Great Dark Spot
Astronomy 20 18
Uranian planets
Cloud Shadows
Universe 6
Astronomy 20 19
Uranian planets
Voyager at NeptuneOther results
6 new moons Proteus 2nd largest Innermost associated
with rings
Proteus
Astronomy 20 20
Uranian planets
Neptune Rings
Rings 2 main rings Thin sheet mysterious thick
spots
Astronomy 20 21
Uranian planets
Magnetic Fields
Neptune's magnetic fieldis tilted like Uranus's.