Astronomy Week 12
(a) Rank the Galilean satellites of Jupiter in order of decreasing size. (b) Rank the Galilean satellites of Jupiter in order of increasing density. (c) Rank the Galilean satellites of Jupiter in order of decreasing distance from Jupiter.
(a) Ganymede, Callisto, Io, Europa (b) Callisto, Ganymede, Europa, Io (c) Callisto, Ganymede, Europa, Io
(a) If Saturn had no moons, what do you suppose its rings would look like? (b) What is the reason for the answer to the previous question?
(a) There would be no rings. (b) Without moons, there would be no material available to be part of the ring system.
What is the evidence for a liquid water ocean on Europa? (Select all that apply.) Why is this interesting to scientists searching for extraterrestrial life?
A weak magnetic field implies the existence of a liquid layer below the surface; Long straight cracks in the icy crust are likely to happen over a liquid subsurface; Europa has jagged blocks of ice that seem to have rotated and collided with each other which cannot happen on a solid moon. Life, as we know it, needs liquid water and life can be found in most places on Earth where liquid water is present.
Based on what you know about the moons of Saturn, select all of the correct statements from the following list.
All of Saturn's moons are a mixture of rock and ice; Smaller moons of Saturn have cracks and smooth areas that suggest past geologic activity; Some of Saturn's moons may have been captured asteroids or Kuiper belt objects; Titan is the only solar system moon with a substantial atmosphere.
Based on what you know about Saturn, select all of the correct statements from the following list.
Being twice as far from the Sun, Saturn is much colder than Jupiter, making its atmosphere much less active; Smaller moons "shepherd" particles in the ring system, or keep them in their rings; Although it has the most extensive one, Saturn is not the only planet with a ring system; Some ring particles are small moons that were pulled apart by tidal forces; Saturn's rings are made mostly of ice particles.
Compare the properties of Titan's atmosphere with those of Earth's atmosphere. (Select all that apply.)
Both atmospheres are mostly nitrogen; Both have weather cycles of evaporation from surface liquid, formation of clouds, and precipitation back onto the surface; Oxygen makes up 20% of Earth's atmosphere.
Pluto's big satellite is called _____.
Charon
If you piloted a spacecraft to visit Saturn's moons and wanted to land on a geologically old surface, what moon would you choose? Why?
Choose a moon with a heavily cratered surface, such as Phoebe. Geologically old surfaces are inactive, and old craters are slowly or never resurfaced as geological features stay in place.
What evidence do we have that the surface of Europa is young and active?
Europa has very few impact craters and the icy crust of Europa is highly reflective.
How can small worlds like Triton and Pluto have atmospheres whereas a larger world such as Ganymede has none?
Farther from the sun, it is colder and easier to retain gases; Most of the atmospheric gases sublimate from ice on the surfaces of the objects.
Explain the energy source that powers the volcanoes of Io.
Io's proximity to Jupiter is such that it experiences tidal heating which is enough to power volcanoes.
How can Titan keep an atmosphere when Titan is smaller than airless Ganymede?
It is twice as far from the sun as Ganymede, so the gases are slower-moving and easier to trap.
The moon Triton orbits which of the planets?
Neptune
Two worlds in the outer solar system that seem remarkably similar to each other are _____.
Pluto and Triton
List at least three major differences between Pluto and the terrestrial planets.
Pluto is much smaller than the terrestrial planets; Its orbit is highly elliptical and inclined to the plane of the ecliptic; It is composed mostly of ice and rock.
Based on what you know about the moons of Jupiter, select all of the correct statements from the following list.
Some of Jupiter's smaller moons are probably captured asteroids; Callisto's old, cratered surface tells us that it has never been geologically active; Ganymede probably was geologically active in the past; Volcanic activity has been observed on Io.
What are the moons of the outer planets made of, and how is their composition different from that of our Moon?
The moons of the outer planets consist of a mixture of ice and rock, whereas our Moon is just rock.
Why do you think the outer planets have such extensive systems of rings and moons, while the inner planets do not? (Select all that apply.)
The temperature is much cooler in the outer solar system which allows ice particles to form and rings are partly composed of these; The outer planets are larger and more massive; The outer plants have more space between them which allows them to accrete more material from the solar nebula to create rings.
Why do you suspect that Triton had a geologically active past? What sources of energy could have powered such activity?
There are few craters; there are cracks in the ice. radioactive decay in it's interior; sunlight
Would you expect to find more impact craters on Io or Callisto? Why?
There are many more impact craters on Callisto because the impact craters on Io are removed (perhaps covered over) relatively rapidly by surface deposits from volcanic activity.
Why are Europa, Ganymede, and Callisto necessary for the continued heating of Io?
These moons periodically tug on Io and keep its orbit elliptical.
When two objects in orbit have periods of revolution that are simple ratios of each other (such as 1 to 2 or 1 to 3) we say that we have _____.
a resonance
The rings of the outer planets consist of _____.
billions of chunks (of various sizes) that all orbit the equator of each planet
Our modern understanding of Pluto is that it is a member of _____.
the Kuiper Belt (of trans-Neptunian objects)
(a) What evidence is there that Pluto and Charon are made of rock and ice? (b) Most of the composition of Pluto and Charon is which of the following?
their densities rock
