Voyagers (1970s) 1800 lbs, dish >12 ft diameter data rates ~115,000 bits/sec (twice dial-up!) Radioisotope Power Generators

Moons Io Europa CallistoGanymede (Covered in the video…)

Galileo Mission ( ) First detection of ammonia in the clouds of Jupiter First detection of ammonia in the clouds of Jupiter Imaged impact by comet Shoemaker- Levy in 1994 Imaged impact by comet Shoemaker- Levy in 1994 Found it likely that there is a 100-km deep ocean under the ice of Europa Found it likely that there is a 100-km deep ocean under the ice of Europa Studied thunderstorms Studied thunderstorms On the way, discovered asteroid Ida has a moon On the way, discovered asteroid Ida has a moon

Saturn Now: In retrograde, rises in ENE at about 10pm and is 60 degrees up at dawn [Fall 2005]

Rings Within Roche Limit (3 body problem…) < 2km thick dust to boulders+

Cassini / Huygens ( ?) Cassini still orbiting Saturn, Huygens probe landed on its moon, Titan, last January Many discoveries, nicely listed in this top-10 list top-10 listtop-10 list

…Huygens probe will be dropped onto Titan What will happen? What will happen? Science News Article, posted Science News Article, posted

Uranus In Aquarius, magnitude 5.7

“Rotisserie” spin during 84-yr orbit 1985 Close to here now

Moons

Neptune 8 th magnitude, in Capricornus

Looks essentially stellar

Neptune’s Moons Giant Triton orbits retrograde, spiraling toward Roche’s limit in 10 – 100 million years Nereid smaller with prograde but very eccentric orbit

Pluto Very faint (15 th magnitude) discovered with 13-inch telescope using at Lowell by Clyde Tombaugh, by examining plates with a blink comparator Orbit within Neptune’s at times (’80-99)

Pluto and Charon One synchronous satellite, discovered in 1978

Two new moons found with HST

New Horizons Mission Launch January, 2006 Swing by Jupiter in 2007 Pass by Pluto/Charon 2015, ASAP, before atmosphere freezes out. Kuiper belt by 2026

Farther out: Short-period comets come from the Kuiper belt P<200 years P<200 years Extends from Neptune’s orbit out to about 1000 AU Extends from Neptune’s orbit out to about 1000 AU Short-period comets are KB objects perturbed toward the sun by the giant planets. Short-period comets are KB objects perturbed toward the sun by the giant planets.

Farther out: Oort Cloud In 1950 Jan Oort noticed that: no comet has been observed with an orbit that indicates that it came from interstellar space, no comet has been observed with an orbit that indicates that it came from interstellar space, there is a strong tendency for aphelia of long period comet orbits to lie at a distance of about 50,000 AU, and there is a strong tendency for aphelia of long period comet orbits to lie at a distance of about 50,000 AU, and there is no preferential direction from which comets come. there is no preferential direction from which comets come. Thus…. Thus….

Long-period Comets perturbed in from Oort Cloud Speaking of comets…