AST 111 Lecture Notes - Lecture 18: Pioneer 10, Soot, Free Surface
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AST 111: Lect 18-Jupiter and Saturn’s Satellites of Fire and Ice
-Jupiter’s Galilean moons
•Discovered by Galileo in January 1610
•Easily seen using binoculars or a small telescope
•They appear to move back and forth
•Short orbital periods
oIo: 1.769 Days
oEuropa: 3.551 Days
2x Io’s orbit
oGanymede: 7.155 days
2x Europa’s orbit
oCalisto
16.689 days
•Prior to spacecraft exploration, a lot of information was obtained by observing
transits, eclipses, and occultations of the satellites
oThe diameters were very well known
oGanymede is the largest satellite and is BIGGER THAN MERCURY!
•Remember the order in which they orbit the planet:
oI (Io)
oEat (Europa)
oGreen (Ganymede)
oCarrots (Calisto)
-The Galilean staellites have been studied using seven spacecraft
•Flybys with Pioneer 10 (1973) and 11 (1974)
-Data from these missions were used to determine the masses and densities of the
Galilean satellites
•Io: 3529 km/m3
•Europa: 3018 kg/m3
•Ganymede: 1936 kg/m3
•Callisto 1851 kg/m3
-The Galilean satellites formed like a mini solar system
•During it’s formation, Jupiter attracted so much matter that it made a miniature
Jovian nebula
-IF Jupiter were about 80 times more massive, it would have become a bona fide star
-Io
•is covered with colorful sulfur compounds ejected from active volcanoes
•It has a very strange surface!
oHas exotic coloring – red, orange, yellow, and black- that come from sulfur
heated and cooled very quickly
oHas many active volcanoes that eject sulfur
No impact crators!!!
•It has the most active surface in the ENTIRE SOLAR SYSTEM
•Io gets its energy from tidal heating