plan for this week the jovian planets 5 major moons comets, asteroids, and earth impacts
TRANSCRIPT
Plan for this week
• The jovian planets• 5 major moons• Comets, asteroids, and Earth impacts
The jovian planets
The jovian planets
• All very large• All rotate very fast• All made mostly of gaseous material
Jupiter
Jupiter
The Great Red Spot
Jupiter
Saturn
Saturn
Uranus
Neptune
Neptune
Data for the jovian planets
Jovian interiors
• At the center, a dense core of rock, metal, and hydrogen compounds
• Around the core is gaseous molecules• Jupiter and Saturn
• Mostly hydrogen• Includes states of matter not found on
Earth• Uranus and Neptune
• Water, methane, hydrogen
The jovian moons
• Some of the jovian moons are far more interesting than the planets themselves
• There are more than 90 total• They come in all sizes
Small jovian moons
Medium sized jovian moons
Largejovianmoons
The jovian moons
• The largest moons in the solar system are:
1. Ganymede (Jupiter)
2. Titan (Saturn)
3. Callisto (Jupiter)
4. Io (Jupiter)
5. ‘The Moon’ (Earth)
6. Europa (Jupiter)
7. Triton (Neptune)
The Galileanmoons
The Galilean moons
• The four largest moons of Jupiter• Discovered by Galileo in the early 1600s
• Very important historically• Proved that everything does not go around the
Earth• Got Galileo in a lot of trouble!
The Galilean moons
• Io• The closest one to Jupiter• Size:
• Larger than Pluto• Smaller than Mercury
• Experiences very strong tidal forces
Tidal forces
Jupiter
(Other moons)
Io
The Galilean moons
• Io is the most geologically active place in the solar system!• Volcanoes continuously erupting• Not a single impact crater on its surface
Io
The Galilean moons
• Europa• The next moon out from Jupiter• Size:
• Larger than Pluto• Smaller than the Moon or Mercury
• Also experiences tidal forces• Surface is entirely covered with ice• May have a water ocean under the ice• A possible place for life?
Europa
Europa
The Galilean moons
• Ganymede• The largest moon in the solar system
• Larger than Pluto and Mercury!• (That’s all you need to know about it…)
Ganymede
The Galilean moons
• Callisto• The fourth one (just for completeness)
Callisto
Saturn’s moons
• Titan• Size:
• The 2nd largest moon in the solar system• Larger than both Pluto and Mercury
• The only moon in the solar system with a substantial atmosphere• Mostly nitrogen (like Earth!)• Atmospheric pressure = 1.5 x Earth’s• Wouldn’t need a space suit! (cold though…)
Titan
Pluto
• The most distant planet - if it’s a planet!• Distance: 30 - 50 AU (40 average)• Orbit = 248 years• Rotation = 6.4 Earth-days• Has one moon: Charon
• About half the size of Pluto
Pluto & Charon
Pluto & Charon
Planetary rings
• All jovian planets have ring systems• All are made of small pieces of debris• Probably unformed moons, or moons that were
broken apart by the planet’s gravity
Saturn’s rings
• Small chunks of ice (mostly)• Incredibly thin
• A single sheet of paper 3 football fields across!• Made of many ‘ringlets’
Asteroids
• Chunks of rock and metal• Mostly in the asteroid belt - but not all of ‘em!• Earth crossing asteroids
• Have orbits that bring them near Earth’s orbit
Comets
• Chunks of ice, rock, & metal (‘dirty snowballs’)• Today in two locations:
• The Kuiper belt• Beyond Neptune’s orbit• ~ 30 - 100 AU out• In the disk of the solar system
• The Oort cloud• A sphere way, way beyond Neptune• ~ 50,000 AU out
A cometnucleus
Comets
• If a comet ‘falls’ towards the Sun:• It begins to sublimate (solid --> gas)• Develops a tail• This tail always points away from the Sun
The Sun