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