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Lecture 11

ASTA01H3 Lecture Notes - Lecture 11: Axial Tilt, Pioneer 11, Escape Velocity


Department
Astronomy
Course Code
ASTA01H3
Professor
Pawel Artymowicz
Lecture
11

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ASTA01 LECTURE NOTES
Lecture 11 Saturn
Gas Giant
Density is less than the water
Gets seasons (belts smeared out)
Belted system similar to Jupiter
Rotation of upper clouds about an hour slower than jupiter
Rings revolve in 4-5 hours (1/2 of the lunar distance per hour speed)
5 visible and large satellites
Mimas, Titan, maybe Hyperion
Rings
62 actual natural moons
Every 29 years things (rings relative to the planet) change, positions change.
Axial tilt is 26.7 degrees.
Titan is the second largest moon in the solar system, (after Ganymede, from Jupiter)
because of the atmospheric composition.
Bigger than mercury, just like Ganymede
Mass: 95.2 Earths
Rotational period of rings is in hours, super quick.
Orbital Eccentricity: 0.0560
Escape velocity: 35.49kms^-1
97% Hydrogen, 3% Helium
Telescopic Observations
Ring system observed in 1610 by Galileo
Thought it was a triple-planet at first
Gave up when it disappeared
Details observed in 1676 by Cassini
Break in the rings
Saw all the basic moons of Saturn
William Herschel
Sees dimmer moons
Dictates that the rotation period is 10H, 16M
INSERT VOYAGER JUPITER MOVIE NOTES HERE
Spacecraft Encounters
Pioneer 11 flew within 21000 km of Saturn in 1979, discovering two new moons, and
measured Saturn’s magnetic field, and found the planet sized moon Titan
We knew that V1 and V2 were already on the way, so P11 used to see if
significant particles were in the ring plate.
Almost smashed into a moon of Saturn
First close-up images of rings and some moons.
Voyager 1 and 2 encounters occurred nine months apart in 1980 amd 1981, discovers
larger of internal to external heat
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