AST Chapter 13 questions
9. When Galileo first saw the moons of Jupiter, what did he think they were?
stars
1. Galileo Galilei, an Italian scientist, was the first person known to use a telescope to study the sky.
true
5. Io orbits faster than any of the other moons - it takes less than 2 days for Io to make a complete orbit. True or False?
true
Most of Saturn's rings lie inside of Saturn's Roche Limit.
true
The Huygens probe fell through Titan's atmosphere and landed on its surface.
true
When is the best time to view Saturn's rings?
when Saturn is in opposition, in the opposite side of the sky as the Sun
Which of the following is NOT a likely size (diameter) of the particles that comprise Saturn's rings?
500 meters
All of the Galilean satellites orbit Jupiter in the same direction. Furthermore, the planes of their orbits all lie within 0.5° of Jupiter's equatorial plane. What does this tell you about the idea that the Galilean satellites formed from a "Jovian nebula"?
A "Jovian nebula" would have flattened into an equatorial plane because of rotation before the Galilean satellites formed, just as the solar nebula did. Thus, this observation provides strong support for this hypothesis.
10. Which of the following was an important effect that Galileo's observations of the moons of Jupiter had on astronomy?
His observation that the moons orbited Jupiter helped convince astronomers that Copernicus's Sun-centered model made better predictions than Earth-centered models.
Many of the gases in the atmosphere of Titan, such as methane, ethane, and acetylene, are highly flammable. Could the atmosphere of Titan ever catch fire?
No. Oxygen is necessary for combustion of these gases, and Titan's atmosphere contains no oxygen.
8. Put the four Galilean moons in order of increasing speed of their orbits around Jupiter:
Callisto, Ganymede, Europa, Io
(a) What aspects of Europa lead scientists to speculate that life may exist there?
Europa may have oceans of liquid water under its surface.
What is the significance of the Roche Limit for a planet?
It is the minimum distance at which a moon can orbit a planet without being torn apart.
Why was the discovery of hydrocarbon lakes near Titan's north pole so significant?
It was the first time that liquids were found on the surface of a Solar System body other than Earth.
What is the structure of Saturn's rings?
Saturn's rings are composed of thousands of ringlets that are organized into the major rings.
How do shepherd satellites operate?
Shepherd satellites operate in pairs to keep ring particles confined to a narrow ring. The outer satellite slows the particles causing them to migrate inward. Then the inner satellite speeds them up again causing them to return to their original orbital distance.
(b) What precautions have been taken to prevent contaminating Europa with Earth organisms?
The Galileo spacecraft was sent to a fiery death in the Jovian atmosphere to avoid contaminating the surface of Europa with Earth organisms.
(b) What evidence is there that ring particles do not migrate significantly between ringlets?
The ring particles are not all the same color. Different colors are caused by chemicals, and they tend to segregate with different colors in different ringlets. These colors have remained constant, suggesting that particles do not migrate significantly between ringlets.
Although the Voyager and Cassini spacecraft did not collect any samples of Saturn's ring particles, measurements from these spacecraft allowed scientists to determine the sizes of the particles. How was this done?
The trajectories of these spacecraft took them behind the rings so that the radio signal to Earth passed through the rings. The degree to which the signal was scattered indicated the particle size.
Io has no impact craters on its surface, whereas our Moon is covered with craters. Why are they different?
Tidal forces from Jupiter make Io very active geologically, and its surface is constantly reformed by volcanic output. This would erase any craters.
2. Jupiter's moons were known to the ancient Greeks, but they did not know what they were. True or false
false
9. Tidal forces will destroy a satellite outside of a planet's Roche Limit.
false
What substance flows through the rivers on Titan's surface?
methane
