Reading: Chapters 1 and 2 in, "The New Solar System", 4th edition
Introduction: A Planetary Perspective
Only in the past few decades have humans realized the importance of studying
our neighbors within the solar system. Beginning with the first launch of Earth-orbiting
satellites in the late 1950's by the former Soviet Union and the United States
of America, and continuing with missions to all planets (except Pluto) in the
solar system, humans began a serious trek toward understanding other worlds.
Currently, Earth's space program represents a relatively unselfish cooperation
among numerous countries, mostly in North America, Europe and Asia.
Much of the impetus for planetary probing resulted from global competition to develop new technology and build better systems for communications, resource evaluation and, of course, national defense. Moreover, we are faced with the overwhelming problem of human population on this planet compounded with dwindling resources.
In his 1993 textbook Moons and Planets, Hartmann (see references below) points out that the idea of space colonization is often associated with the concept of utilizing resources obtained on other planetary bodies. He reminds us that environmental awareness on Earth has taught us three important lessons in planetary science:
- (1) Major social changes occur on Earth because finite supplies of materials are running out.
- (2) We need to avoid large-scale tampering with Earth's ecosystems because of the complex (and often incomprehensible) interactions between biological and nonbiological components of Earth's systems.
- (3) "Gluttonous consumption destroys beautiful, unique, and scientifically valuable resources."
People first went to the Moon in 1969 on the Apollo 11 mission and returned safely with precious lunar rocks and soils. We have maintained space stations around Earth and demonstrated the utility of performing experiments and developing technology in near zero-gravity regimes. In the summer of 1997, the entire world witnessed the first Mars Pathfinder mission and saw a small-wheeled robot called Sojourner roll off a ramp and away from its parent capsule to analyze rocks on the martian surface.
Many pathfinder sites start from: http://mars.jpl.nasa.gov/default.htm
There is little wonder in why we intend to explore our solar system, but we have to be efficient in our means of travel and scientific inquiry. A high level of efficiency depends on using what knowledge is gained from previous studies to evaluate the best means of developing and utilizing future studies. All disciplines of science, engineering, humanities, art, law, medicine, and other facets of human society are becoming involved in planetary exploration and development. We need to learn as much as possible about our neighbors in the solar system so that we make wise decisions concerning the fate of natural resources, ecosystems, and humanity itself!
The Solar System -- Overview
Below are links to excellent sites that you may want to really get to know. Pick a few of your favorites to use during this and the other modules. There are many, many, many !!! more, but if you aren't careful you will get caught up in trying to search too many. That's why pick a few of your favorites to bookmark for future reference.
If you know the order of the planets, your life will be easier for the rest of this course. So take some time to learn the order before proceeding.
Use this mnemonic: . . ."My Very Excellent Mother Just Sent Us Nine Pizzas."
The Solar system = one star + nine planets + about 60 moons + thousands of asteroids + billions of meteoroids and comets -- PLUS THOUSANDS OF PIECES OF SPACE JUNK ORBITING THE EARTH!
The Sun makes up about 99.87 percent of the mass of the solar system (Jupiter has most of the rest!)
View a general table of planetary characteristics, and notice how the planets compare to each other and to the other celestial bodies.
Assignment # 1
Answer these questions using complete sentences. Be as brief but still complete and accurate as possible.
A. What is basalt, and where is it found? Why?
B. What ices dominate the solar system?
C. Where do asteroids fit into the Solar System?
D. Are asteroids found in particular orbits? Why or why not?
E. Where are comets found? Are all comets the same?
F. Planetary Bodies: Planets, Moons, Asteroids, Comets:
1. What are the general differences between planets, moons, asteroids, and comets?
2. What do the inner planets have in common with each other in terms of size, location, and composition?
3. What do the outer giant planets have in common with each other?
G. Planetary Motion:
1. In what way(s) are the orbits of Venus and Uranus different from those of other planets?
H. Planetary Exploration :
1. Without going into details, what major events (i.e. missions or series of missions) contributed most to our understanding of each of the planetary bodies?2. What single event caused the instantaneous rise in interest in space exploration in the United States?
I. Processes:
1. List several of the most important planetary processes responsible for the existence of planetary bodies as they are now.2. Pick two planets. Write a one sentence description of each planet's surface. Then write a one sentence explanation for the difference between the surfaces.
J. Projects:
1. If you had "unlimited" resources, what would you provide to the general public to promote a better understanding of our solar system, its resources, and its planetary environments?
Advanced Topics :
8. Do terrestrial planets normally have moons? The answer to this question is not simple, nor is there any correct one. We have not begun to assess the causes of moon formation, but you can get the idea by focussing on the number of inner planets vs. outer planets that have moons and the processes that might have resulted in the existence of moons for each of those planets.Just for fun let's put the Solar System into perspective:
If the Sun were 3 m in diameter (about the height of a basketball hoop) then . . . .
- Mercury would be ~10 mm or about the size of a shirt button and be 128 m (0.08 mi) from the sun.
- Venus would be 27 mm or a U.S. half-dollar and be 238 m (0.15 mi) from the sun.
- Earth would be 28 mm (U.S. silver dollar) and 326 m (0.20 mi) from the sun.
- Our Moon would be about 8 mm (a small button).
- Mars would be 15 mm or the size of a marble and 500 m (0.31 mi) from the sun.
- Asteroids = 1-2 mm (big ones, just pinheads) @ ~880 m (0.55 mi) distance.
- Jupiter = 32 cm (medicine ball) @ 1,707 m (1.1 mi) distance.
- Saturn = 27 cm (basketball) @ 3,130 m (2.0 mi) distance.
- Uranus = 11.3 cm (softball) @ 6,300 m (3.9 mi) distance.
- Neptune = 10.9 cm (softball) @ 9,900 m (6.2 mi) distance.
Okay, those weren't all that accurate, but they help. Here are the Actual Solar System Dimensions:
Planetary Body |
Diameter Relative to Earth |
Diameter (km) |
Average Distance from Sun Relative to Earth's Diameter |
Average Distance from Sun (106 km) |
| Sun | 109.0 | 1,390,400 | -- | |
| Mercury | 0.383 | 4,886 | 4,540 | 59.7 |
| Venus | 0.948 | 12,093 | 8,480 | 108.2 |
| Earth | 1.000 | 12,756 | 11,700 | 149.2 |
| Moon | 0.273 | 3,482 | 30.2* | |
| Mars | 0.533 | 6,799 | 17,900 | 228.3 |
| Jupiter | 11.200 | 142,867 | 61,000 | 778.1 |
| Saturn | 9.450 | 120,544 | 112,000 | 1,429 |
| Uranus | 4.020 | 51,279 | 225,000 | 2,870 |
| Neptune | 3.880 | 49,493 | 352,000 | 4,490 |
| Pluto | 0.180 | 2,296 | 463,000 | 5,906 |
| * Average Distance from the Earth | ||||
Assignment # 2
Study the Planetary Data Table below, for general relations to Earth. Compare to this table. Draw some conclusions about where each type of planet occurs in the solar system and write down the possible reasons for the size and location of each planet. E-mail your conclusions and reasons to us. Save your file for later comparisons
Solar System data in terms of Earth:
Planetary Body |
Orbital Period |
Volume |
Mass |
Surface Gravity |
Rotational Period |
| Sun | -- | 1,300,000 | 333,000 | 28.00 | 24.6* |
| Mercury | 0.241 | 0.056 | 0.055 | 0.37 | 58.7 |
| Venus | 0.615 | 0.860 | 0.815 | 0.91 | -243.0+ |
| Earth | 1 | 1 | 1 | 1 | 1 |
| Moon | 0.0748 | 0.020 | 0.012 | 0.170 | 27.3 |
| Mars | 1.88 | 0.150 | 0.107 | 0.380 | 1.03 |
| Jupiter | 11.9 | 1300.0 | 318.0 | 2.300 | 0.411 |
| Saturn | 29.5 | 760.0 | 95.2 | 0.880 | 0.428 |
| Uranus | 84.0 | 50.0 | 14.5 | 0.960 | -0.720+ |
| Neptune | 165.0 | 45.0 | 17.1 | 1.300 | 0.671 |
| Pluto | 248.0 | 0.0055 | 0.0023 | 0.073 | 6.390 |
| *Rotational period at the equator of the Sun. | |||||
| +Rotation is retrograde, opposite to rotation of the Earth. | |||||
Review the General Properties of all Planets, the Major Moons, Asteroids and Comets in book
Assignment # 3
Find four specific examples of technology developed for the space program that have been applied to other areas. For example, the plastic, Lexan, was developed for use in space, and is now found in everything to light weight cutlery for backpacking to firehose nozzles to unbreakable windows.
Write a short description of the material, the original application, and current applications.
E-mail your document along with the other two assignments to mailto:hughscot@isu.edu.
Vocabulary list to know:
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Some other websites that might be helpful:
P.O.E.T.R.Y. K-12 Space Science Site
Students for the Exploration and Development of Space
The Nine Planets - A Multimedia Tour of the Solar System
Lunar and Planetary Institute -- They have several slide sets that we will use throughout
this course, but for now visit
References
Greeley R. (1993) Planetary Landscapes. Chapman and Hall, New York. 286 pp.
Hartmann, W.K., 1993, Moons and Planets, 3rd edition. Belmont, CA: Wadsworth Publishing Company.