Class 18: Jovian Planets and Their Moons

In this class, we will explore the characteristics of the four Jovian planets: Jupiter, Saturn, Uranus, and Neptune.

• Jupiter: The largest planet in our solar system, known for its Great Red Spot and extensive moon system, including the four largest moons called the Galilean moons.

• Saturn: Famous for its stunning ring system, Saturn also has numerous moons, with Titan being the most significant due to its thick atmosphere and liquid methane lakes.

• Uranus: An ice giant with a unique tilt that causes extreme seasonal variations, it has a faint ring system and 27 known moons.

• Neptune: The furthest planet from the Sun, known for its intense blue color and strong winds, it also has a ring system and several moons, including Triton, which is geologically active.

• compared to terrestrial planets, the Jovian planets are composed mainly of hydrogen and helium; atmosphere is thick with gas than transitions to liquid, then solid; their masses are high; they spin quickly; all Jovian planets have rings; many moons

Jupiter

• Largest planet in the solar system

• mass is 317.8x the Earth’s

• thick, gaseous atmosphere composed primarily of hydrogen and helium, with trace amounts of methane, water vapor, ammonia, and other compounds.

• its density increases towards the centre

• has very faint rings

• has 79 detected moons so far

Jupiter’s Interior

• Jupiter’s composition used to have differentiation, but after a collision, its core is now diluted

Jupiter’s storms

• winds of up to 500km/h, with wind bands up to 3000km thick (reasons for which are not fully understood yet)

Jupiter’s clouds

• the temperature and pressure vary as you enter Jupiter: the lower the altitude, the higher the temperature and pressure become, causing different molecules to form different clouds

• ammonia clouds are white: they are higher in altitude and cooler, therefore emit less infrared light

• ammonium hydrosulfide clouds are orange: they are lower in altitude and warmer, therefore are brighter in infrared photos

Saturn

• Second largest planet

• close to the same size and structure as Jupiter, but has 3.3x less mass

• has spectacular rings

• 82 observable moons so far

Saturn’s Rings

• the rings span to be over 260,000km in diameter, but each ring is less than 0.1km thick (weird?)

Uranus & Neptune

Uranus

• the coldest planet

• has a small rocky core, its mantle composed of thick water, ammonia, and methane

• atmosphere composed of thick hydrogen and helium

• its rotation axis is tilted at 98 degrees, resulting in extreme seasons and unique weather patterns that differ significantly from those of other planets in the solar system.

Neptune

• furthest planet from the sun

• structure very similar to uranus

• rotation axis tilted at 28 degrees

• has more surface features than uranus

• Has the strongest winds in the solar system, as fast as 2100km/h

Interiors of Uranus & Neptune

• Core: rock and ice

• followed by a mantle made of thick water, ammonia, and methane gas

• followed by a thick atmosphere of hydrogen and helium with some methane gas

• uranus and neptune are very similar, and are called the ice giants

The Galilean Moons: The 4 Large Moons of Jupiter

Io

• the most geologically active object in the solar system, and is around the same size as Earth’s moon

Europa

• Surface covered with un-cratered ice, and is smaller than the Earth’s moon

• they may be a huge ocean covering the moon underneath the surface

Ganymede

• A little larger than the Earth’s moon

• Surface has some cratering, along with ancient geological activity

Callisto

• a little smaller than Ganymede

• heavily cratered surface

Saturn’s Moons

Titan

• Saturn’s largest moon

• its surface features are hidden by thick clouds

• titan has an atmosphere; its thick clouds hide Titan’s surface features, but can be seen using infrared cameras

• radar images show seas with changing coastlines on Titan

• despite these features, it is inhabitable

Iapetus

• Very old cratered surface

• mostly made of ices

• there is a giant ride along the equator

Rhea

• Heavily cratered ball of ice

• Cassini (probe) gravity measurements indicate that it may not be differentiated (not homogenous inside)

Enceladus

• One of the most reflective objects in the solar system (very high albedo)

• some parts are cratered and some aren’t (due to active methane geysers)

• enceladus is relatively small and yet is geologically active…

Hyperion

• made mostly of water and ice

• heavily cratered

• very porous: 40% empty space

Uranus’ Moons

Miranda

• some craters along with strange geological features

• high ice content

Neptune’s Moons

Triton

• Very cold, with a temp of -235 degrees C

• surface is mainly frozen nitrogen

• almost no atmosphere

• Geologically active, but with water and ammonia instead of lava

• Orbits Neptune backwards

• it is probably a captured dwarf planet that has been influenced by Neptune's gravity, leading to its unique orbital characteristics.