Bands & Zones, Atmosphere, Rotation

Red spot

Ring

Satellites

Amalthea

Galilean: original Io - Volcanoes

Europa - cracks - smallest

Ganymede - largest, grooved terrain

Callisto - heavily cratered

Outer satellites: captured asteroids

Atmosphere, rotation

Rings - A, B, C - Cassini's division, F ring, Shepherd satellites,

Roche's Limit

Satellites Discussed:

Mimas - "Death Starof

Enceladus - smooth, high albedo, geo-active

Tethys - ice, craters

Dione - ice, craters, leading and trailing sides

Rhea - ice, craters

Titan - largest, thick, dense, opaque, N, atmosphere

Hyperion - "hamburger" shaped

Iapetus - 1/2 black, 1/2 white

7th planet, barely visible to naked eye, greenish disk gas giant, = 1/3 diam. of Jupiter (52,000 km.)

Discovered by Wm. Herschel 1781

Unusual axial tilt (obliquity)

Has 15 satellites and rings (small: 400-1600 km.) - all orbit in equatorial plane - formed after obliquity established

Voyager 2, 1986

Atmosphere: mostly hydrogen and helium (=10-12%), methane blue-green color

Almost totally devoid of detail. Methane ice crystals (clouds).

Atmosphere & internal Structure: Hydrogen & helium with liquid water layer and solid core

Rings: discovered 1977 during occulation expt. at least 10 rings - dark, can't be seen directly from earth probably rocky, not icy

- Discovered by German astronomer using calculations by Adams & Leverrier based on perturbations of Uranus' orbit - 1846

- Appears similar to Uranus in size, internal structure, atmospheric composition

- Rings recently discovered - Voyager

- 28⁰ 48' obliquity

- Satellites: 2 known previously, six more discovered by Voyager

- Triton: largest satellite of Neptune (3,500 km.).
Has atmosphere w/ methane

- Retrograde orbit, 6 days

- 20^o inclination

- Nereid - 500 km. diameter, Prograde orbit, very eccentric

1.6 million km x 9.6 million km

Voyager 2 - Neptune in 1989

VOYAGER MISSION TO NEPTUNE

Two Voyager spacecraft were launched in 1977 from Kennedy Space Center in Florida. Vovager I flew by Jupiter in March 1979 and Saturn in November 1980. Voyager 2 flew by Jupiter in July 1979, Saturn in August 1981, Uranus in January 1986 and Neptune in August 1989. The two spacecraft are now traveling out of the solar system into interstellar space -- searching for the heliopause, or the outer boundary of the Sun's energy influence.

Slide Number Description

1 False-color image of Neptune. Red areas are semitransparent haze covering planet

2 Neptune's Great Dark Spot, accompanied by white high-altitude clouds.

3 Cloud svstems in Neptune's southern hemisphere.

4 Neptune through various camera filters. Views reveal altitude data on cloud features.

5 Great Dark Spot. This storm system rotates counterclockwise.

6 High-altitude cloud streaks in Neptune's atmosphere.

7 Two views of satellite 1989N2. Dark, irregularly shaped moon was discovered by

Voyager 2.

8 Satellite 1989NI, discovered by Voyager 2.

9 Neptune's ring system, shown in two exposures lasting neafly 10 minutes each.

10 Detail of Neptune's rings.

11 Bright southern hemisphere on Triton.

12 View about 300 miles across Triton's surface

13 Triton from 80,000 miles. Long feature is probably a narrow down-dropped fault block.

14 Triton's south polar terrain. About 50 dark plumes mark what may be ice volcanoes.

15 Triton from 25,000 miles. Depressions may be caused by melting and collapsing of icv surface.

16 Computer-generated perspective view of one of Triton's caldera-like depressions.

17 High-resolution color mosaic of Triton.

18 Triton just after closest approach.

19 Post-encounter view of Neptune's south pole.

20 Neptune and Triton 3 days after flvbv. Triton is smaller crescent and is closer to viewer.