Lecture 7: Jovian Planets, Lecture notes of Astronomy

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JOVIAN

PLANETS

LECTURE 7

AKA Gas Giants Large size and large mass Less dense Many moons Has rings Huge atmospheres Further away from the Sun - much cooler Much more spread apart Large magnetic spheres (orbits very slowly) Fast rotation (short days but very long years) I. INTRO II. JUPITER C h a r a c t e r i s t i c s Largest planet in our solar system (approximately 11 times wider than Earth). Made mostly of hydrogen and helium; no solid surface. Has the fastest rotation on its axis. Largest magnetic field (caused by metallic hydrogen and fast rotation). Has 79 moons, including the four large ones (Io, Europa, Ganymede and Callisto). 1 rotational spin takes less than 10 hours a day. Fifth planet from the Sun and approximately 484 million miles away. Has faint rings made of dust particles. Red spots on Jupiter were caused by a huge storm raging about 400 years ago.

Largest Moon in the solar system (bigger than Mercury). The only Moon with its own magnetic field. Two types of terrain: dark and heavily cratered regions, and lighter areas with grooves and ridges. Possibly also have water due to its icy crust. Has a thin atmosphere composed primarily of oxygen (but far too thin to sustain human life). Takes 7 Eath days for Ganymede to fully complete one orbit around Jupiter. GANYMEDE II. JUPITER G A L L I L E O M O O N S : Has the oldest and heavily cratered surfaces in the solar system. Surface remained unchanged for approximately 4 billion years (preserving a record of the early solar system history). Mix of ice and rocks. Believed to have a salty ocean layer beneath the icy crust, similar to Europa. Has very thin atmosphere, mostly made of carbon dioxide. No tectonic or volcanic activity. Feature: Valhalla Basin, a massive crater with a series of concentric rings (made by a massive collision with asteroid or comet. CALLISTO

III. SATURN 2nd largest planet in the solar system. Have the most visible and gorgeous rings that are made up of ice, rock and dust particles. No solid surface, mostly hydrogen and helium. Fast rotation (takes 10.7 hours to complete one rotation on its axis). Has 83 confirmed Moons. Known for strong winds and massive storms. Strong magnetic field, which creates a radiation belt around the planet. Pale yellow appearance because of the ammonia clouds in its atmosphere. Density is lower than water. M O O N : The only moon in the solar system with a dense atmosphere made of nitrogen, methane and ethane (which gives the sky it’s orange hazy tint). Larger than Mercury. Has lakes, rivers and seas but not water (filled with ethane and methane), Largest moon of Saturn. Seasons last for ~7.5 Earth years due to its tilted axis. TITAN

VIII. PLUTO IX. MAIN MOONS C H A R A C T E R I S T I C S : Once considered the ninth planet in the solar system but reclassified as a dwarf planet in 2006 due to its small size. Discovered in 1930s by Clive Tombaugh. Has highly elliptical and tilted orbit. 1 orbit around the Sun = 248 Earth years. Surface is mostly covered in nitrogen ice with methane and carbon monoxide ice. Some regions are reddish-brown color due to presence of complex organic molecules called “tholins”. Has 5 moons, with Charon (1978) being the largest (bigger than Pluto). Around 227 Moons are known in the solar system. Smaller moons are not spherical in shape. Largest to smallest: O F T H E S O L A R S Y S T E M

1. Ganymede (Jupiter)
2. Titan (Saturn)
3. Callisto (Jupiter)
4. Io (Jupiter)
5. Moon (Earth)
6. Europa (Jupiter)
7. Triton (Neptune)
8. Titania (Uranus)
9. Rhea (Saturn)
10. Oberon (Uranus)
11. Lapetus (Saturn)
12. Charon (Pluto)
13. Ariel (Uranus)
14. Umbriel (Uranus)
15. Dione (Saturn)
16. Tethys (Saturn) (rest are smaller moons in diameters)