Voyagers (1970s)

1
Voyagers (1970s)

• 1800 lbs, dish gt12 ft diameter
• data rates 115,000 bits/sec (twice dial-up!)
• Radioisotope Power Generators

2
Moons
(Covered in the video)
Io
Europa
Callisto
Ganymede
3
Galileo Mission (1989-2003)

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

4
Saturn
Now In retrograde, rises in ENE at about 10pm
and is 60 degrees up at dawn Fall 2005
5
Rings

• Within Roche Limit (3 body problem)
• lt 2km thick
• dust to boulders

6
Cassini / Huygens (1997 - ?)

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

7
Huygens probe will be dropped onto Titan

• What will happen?
• Science News Article, posted

8
Uranus

• In Aquarius, magnitude 5.7

9
Rotisserie spin during 84-yr orbit
Close to here now
1985
10
Moons
11
Neptune
8th magnitude, in Capricornus
12
Looks essentially stellar
13
Neptunes Moons

• Giant Triton orbits retrograde, spiraling toward
  Roches limit in 10 100 million years
• Nereid smaller with prograde but very eccentric
  orbit

14
Pluto

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

15
Pluto and Charon

• One synchronous satellite, discovered in 1978

16
Two new moons found with HST
17
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

18
Farther out Short-period comets come from the
Kuiper belt

• Plt200 years
• Extends from Neptunes orbit out to about 1000 AU
• Short-period comets are KB objects perturbed
  toward the sun by the giant planets.

19
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,
• 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.
• Thus.

20
Long-period Comets perturbed in from Oort Cloud
Speaking of comets