astro 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
Compare the properties of Titan's atmosphere with those of Earth's atmosphere.
- 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. - Both atmospheres are mostly nitrogen
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
List at least three major differences between Pluto and the terrestrial planets.
- It is composed mostly of ice and rock. - Its orbit is highly elliptical and inclined to the plane of the ecliptic. - Pluto is much smaller than the terrestrial planets.
What is the evidence for a liquid water ocean on Europa?
- 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. - A weak magnetic field implies the existence of a liquid layer below the surface.
Based on what you know about Saturn, select all of the correct statements from the following list.
- 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. - Saturn's rings are made mostly of ice particles.
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 - Ganymede probably was geologically active in the past - Volcanic activity has been observed on Io.
Based on what you know about the moons of Saturn, select all of the correct statements from the following list.
- Some of Saturn's moons may have been captured asteroids or Kuiper belt objects. - Smaller moons of Saturn have cracks and smooth areas that suggest past geologic activity. - All of Saturn's moons are a mixture of rock and ice.
Why do you think the outer planets have such extensive systems of rings and moons, while the inner planets do not?
- 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. - The temperature is much cooler in the outer solar system which allows ice particles to form and rings are partly composed of these.
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 outer plants have more space between them which allows them to accrete more material from the solar nebula to create rings. - 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.
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 its interior; sunlight
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.
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
If Saturn had no moons, do you think it would have rings? Why or why not?
No, the rings are formed from collisions between moons and asteroids or comets.
Two worlds in the outer solar system that seem remarkably similar to each other are _____.
Pluto and Triton
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.
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 and Ganymede 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)
What evidence is there that Pluto and Charon are made of rock and ice?
their densities
