Jessie Horn: Chapter 8 Quiz

Quiz

1. What are jovian planets made of?  Jupiter and Saturn are made almost entirely of hydrogen and helium  while Uranus and Neptune are made mostly of hydrogen compounds mixed with metal and rock. These differences arose because all four planets started from ice rich planetesimals of about the same size but captured different amounts of hydrogen and helium gas from the solar nebula. 
2. What are jovian planets like on the inside? The jovian planets have layered interiors with very high internal temps and pressures. All have a core about 10 times as massive as Earth, consisting of hydrogen compounds, metals  and rock. They differ mainly in their surrounding layers of hydrogen and helium, which can take on unusual forms under the extreme internal conditions of the planets. 
3. What is the weather like on jovian planets? The jovian planets all have multiple cloud layers that give them distinctive colors, fast winds, and large storms. Some storms, such as the Great Red Spot, can apparently rage for centuries or longer. 
4. What kinds of moons orbit the jovian planets? We can categorize the sizes of the many known moons as small, medium, or large. Most of the medium and large moons probably formed with their planet in the disks of gas that surrounded the jovian planets when they were young. Smaller moons are often captured asteroids or comets. 
5. Why are Jupiter's Galilean moons geologically active? io is the most volcanically active object in the solar system, thanks to an interior kept hot by tidal heating-which occurs because Io's close orbit is made elliptical by orbital resonance with other moons. Europa and possibly Ganymede may have a deep, liquid water ocean under its icy crust, also due to tidal heating. Callisto is the least geologically active, since it has no orbital resonance or tidal heating. 
6. What geological activity do we see on Titan and other moons? Titan, the only moon in our solar system with a thick atmosphere, shows evidence of active surface geology, including erosion caused by methane rain. Other medium-size moons of Saturn and Uranus show evidence of past geology. Saturn's moon Encladus is geologically active today, as evidenced b y fountains of ice and water vapor that shoot out from its surface. Neptune's large moon Triton is almost certainly a captured object and also shows evidence of recent geological activity. 
7. Why are jovian moons more geologically active than small rocky planets? Ices deform and melt at much lower temps than rock, allowing icy volcanism and tectonics at surprisingly low temperatures  In addition, some jovian moons have a heat source, tidal heating, that is not important for the terrestrial worlds. 
8. What are Saturn's rings like? Saturn[s rings are made up of countless individual particles, each orbiting Saturn independently like a tiny moon. The rings lie in Saturn's equatorial plane, and they are extremely thin.
9. Why do the jovian planets have rings? Ring particles probably come from the dismantling of small moons formed in the disks of gas that surrounded the jovian planets billions of years ago. Small ring particles come from countless tiny impacts on the surfaces of these moons, while larger ones come from impacts that shatter the moons. 
10. Who predicted volcanoes on Io? Shortly before the Voyager 1 encounter, Stan Peale, Patrick Cassen, and R. T. Reynolds published a paper in the journal Science predicting a volcanically modified surface and a differentiated interior, with distinct rock types rather than a homogeneous blend. They based this prediction on models of Io's interior that took into account the massive amount of heat produced by the varying tidal pull of Jupiter on Io caused by the moon's slightly eccentric orbit. Their calculations suggested that the amount of heat generated for an Io with a homogeneous interior would be three times greater than the amount of heat generated by radioactive isotope decay alone. This effect would be even greater with a differentiated Io.