What are the two agreed upon defining characteristics of a planet?
Compare the characteristics of a terrestrial planet to that of a Jovian planet.
In what ways are the largest moons similar to the terrestrial planets? In what ways are they different? Which moons are largest?
What is meant by the average density of a planet? Do all the planets orbit the Sun in the same direction? Are all of the orbits circular?
What is an asteroid? What is a trans-Neptunian object? In what ways are these minor members of the solar system like or unlike the planets?
What are the asteroid belt, the Kuiper belt, and the Oort cloud? Where are they located? How do the objects found in these three regions compare?
In what ways is Pluto similar to a terrestrial planet? In what ways is it different?
What is the connection between comets and the Kuiper belt? What is the connection between comets and the Oort cloud?
Imagine a trans-Neptunian object with roughly the same mass as Earth but located 50 AU from the Sun. (a) What do you think this object would be made of? Explain your reasoning. (b) On the basis of this speculation, assume a reasonable density for this object and calculate its diameter. How many times bigger or smaller than Earth would it be?
What is the nebular hypothesis?
What is a protosun? What causes it to shine? Into what does it evolve?
What are proplyds? What do they tell us about the plausibility of our model of the solar system’s origin?
(a) What is meant by accretion? (b) Why are the terrestrial planets denser at their centers than at their surfaces?
Explain how our current understanding of the formation of the solar system can account for the following characteristics of the solar system: (a) All planetary orbits lie in nearly the same plane. (b) All planetary orbits are nearly circular. (c) The planets orbit the Sun in the same direction in which the Sun itself rotates.
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Explain why most of the moons of Jupiter orbit that planet in the same direction that Jupiter rotates.
What are the differences between radial velocity and the transit method of extrasolar planet detection?
Propose an explanation of why the Jovian planets are orbited by terrestrial-like moons.
Suppose that a planetary system is now forming around some protostar in the sky. In what ways might this planetary system turn out to be similar to or different from our own solar system? Explain your reasoning.
Suppose astronomers discovered a planetary system in which the planets orbit a star along randomly inclined orbits. How might a theory for the formation of that planetary system differ from that for our own?
Imagine that scientists are proposing to send a robotic lander to visit Jupiter’s Callisto. Create a 100-word written proposal describing why you would most like to send a robotic lander to another one of the Galilean moons. Explain why your group found it to be the most interesting and why the government should allocate the money for your alternative project. In your proposal, be sure to demonstrate your knowledge of Callisto and at least one other moon.
Find objects in the room or among your possessions that can be used to create a reasonably accurate scale model of the planets of our solar system. Try finding a small object to represent Mercury first.
Use Starry Night™ to observe the motions of two smaller objects in the solar system, the dwarf planet Ceres and the minor planet Pallas, both members of the asteroid belt, as seen from Earth. Open Favourites > Explorations > Atlas to view the sky from the center of a transparent Earth. Select View > Ecliptic Guides > The Ecliptic from the menu and set the Time Flow Rate to 1 sidereal day. Open the Find pane, type the name Ceres in the search box, and press the Enter key to center the view on this dwarf planet. Click the Play button and observe the motion of Ceres over the course of at least two years of simulated time. (a) Describe how Ceres moves. (b) How can you tell that Ceres orbits the Sun in the same direction as the planets? (c) Return to the Find pane, type the name Pallas in the search box, and press the Enter key to center the view upon this minor planet. Watch the motion of Pallas in the sky for at least two years of simulated time. How does the motion of Pallas compare with that of Ceres? (d) Which object’s orbit is more steeply inclined to the plane of Earth’s orbit? How can you tell?
Use Starry Night™ to explore some of the dwarf planets of the solar system. Select Favourites > Explorations > Dwarf Planets from the menu. This view, from a position in space about 97 AU from the Sun, shows Neptune’s orbit as well as the orbits of several dwarf planets. Right-click (Ctrl-click on a Mac) on the Sun and select Centre from the contextual menu. (a) Do the dwarf planets revolve about the Sun in the same or opposite direction as the major planets? (b) Use the location scroller to adjust the view so that the plane of Neptune’s orbit appears edge-on. How do the orbital planes of the dwarf planets compare to those of the planets?
Use Starry Night™ to observe a comet. Select Favourites > Explorations > Hale-Bopp. (a) From the appearance of this comet, predict the direction of the Sun relative to the comet and explain how you made your prediction. Use the hand tool to find the Sun in the view to verify your hypothesis. (b) Select File > Revert from the menu. From the appearance of the comet, can you predict what its motion will be in the future against the background stars? Click the Play button to see if your prediction was correct.
Use Starry Night™ to make observations of the solar system. Select Favourites > Explorations > Solar System. The view shows the names and orbits of the major planets of the solar system against the backdrop of the stars of the Milky Way Galaxy, from a location hovering 64 AU from the Sun. You may also see many smaller objects moving in the asteroid belt between the orbits of Mars and Jupiter. (If not, select View > Solar System and click on the Asteroids box.) (a) Use the location scroller to look at the solar system from different angles, and observe the general distribution and motion of the major planets. Make a list of your observations. (b) How does the nebular hypothesis of solar system formation account for your observations?
Use Starry Night™ to investigate stars that have planets orbiting them. Click the Home button in the toolbar. Open the Options pane and use the checkboxes in the Local View layer to turn off Daylight and the Local Horizon. Expand the Stars layer in the Options pane and then expand the Stars item and check the Mark stars with extrasolar planets option. Then use the Find pane to find and center each of the stars listed below. To do this, click the magnifying glass icon on the side of the edit box at the top of the Find pane and select Star from the drop-down menu; then type the name of the star in the edit box and press the Enter or Return key on the keyboard. Click on the Info tab for full information about the star. Expand the Other Data layer and note the luminosity of each of these stars. (a) Which stars are more luminous than the Sun? (b) Which are less luminous? (c) How do you think these differences would have affected temperatures in the nebula in which each star’s planets formed? (i) 47 Ursae Majoris (three known planets); (ii) 51 Pegasi (one known planet); (iii) 70 Virginis (one known planet); (iv) Rho Coronae Borealis (one known planet).