Download Our own Earth`s interior structure, and surface features will be

Homework # 3 is due October 21. See syllabus for details.
Lecture Summary (10/12 & 10/14)
Landers, orbiters, and rovers have been exploring Mars over the last 4 decades. Views
from the surface taken by the Martian rovers were shown.
Asteroids lie mostly between the orbits of Mars and Jupiter, yet some have Earth-crossing
orbits. Recently probes have flown past Halley's comet, and 4 asteroids, if you include Dactyl.
The near-Earth asteroid, Eros, was studied during the NEAR mission.
The extreme drop in the intensity of sunlight was highlighted before moving to planets of
the outer solar system. Jupiter was used to introduce the jovian planets (Jupiter, Saturn, Uranus,
Neptune). These planets are massive, large, have many moons, ring systems, and low densities.
Jupiter’s Great Red Spot is an atmospheric feature. Saturn’s rings lie within the Roche Limit as
do the other ring systems. Magnetic fields for jovian planets result from an interior region
comprised of liquid metallic hydrogen. Inside each of these planets is a rocky core. Three outer
solar system moons were discussed: Io (Jupiter), Europa (Jupiter) and Titan (Saturn). Latest
information from spacecraft provides new insights to these interesting worlds. Future missions to
Europa and Titan were considered.
Pluto doesn’t really fit in with either the terrestrial or jovian planets. If it were
discovered today (rather than in 1930), Pluto would most likely be classified as a Kuiper Belt
Object. However, in 2000 the International Astronomical Union voted to keep Pluto as the ninth
planet. Other sizeable bodies reside beyond Pluto’s orbit, but it is unlikely that any of these will
ever be classified as a tenth planet.
Halley first noticed the periodic nature of comets. The very eccentric orbit of Halley's
Comet brings it closer to the Sun than Venus and it swings out farther than Neptune. Mrs.
Deming used dry ice and fluorescent materials to illustrate some of the properties of comets.
Most of a comet's time is spent in the cold regions of the Solar System, but as it approaches the
Sun, sublimation of ices from the nucleus allows the coma and tail to form. Unlike the gas tail
which is pushed out of the Solar System by the solar wind, the small bits of rock and dust from
the nucleus continue to orbit the Sun.
Kuiper belt objects and the Oort cloud were cited as the sources of comets. When a
comet passes an outer planet, its orbit can be changed by gravitational effects.
TERMS: Spirit and Opportunity landers/rovers, inverse square law, asteroid, asteroid
belt, Galileo orbiter, Cassini mission, dwarf planet, comets, coma, sublimation, fluorescence,
nucleus, tail, Oort Cloud, Kuiper Belt,
QUESTIONS:
1. What observations have the martian rovers made?
2. Describe the appearance of an asteroid based on images taken by the Galileo and NEAR
missions.
3. Where are most asteroids found? Do any come near Earth? Explain.
4. How is Jupiter different from Earth?
5. What is the Great Red Spot?
6. Why do jovian planets have magnetic fields?
7. Why does a planet like Saturn have rings?
8. Why do Uranus and Neptune appear blue?
9. Why are Io, Europa, and Titan such interesting bodies?
10. How would you classify Pluto? Explain
11.. Explain how and why a comet changes as it moves through one complete orbit.
12. How does angular size and fluorescence contribute to increasing a comet’s visibility?
13. Compare the Kuiper Belt to the Oort Cloud.
14. Compare asteroids to comets.