Table Of Contents [an error occurred while processing this directive] previous page [an error occurred while processing this directive] next page

The subject of planetary exploration - much of it relying exclusively or largely on remote sensing - has, since the space age, become one of incredible and vast accomplishments in which huge amounts of data have now accumulated. It is, regrettably, impractical owing to the limitations of Web space allotted to this Tutorial to go into these fascinating results in the detail that this writer (NMS) - a onetime planetologist before entering the field of terrestrial remote sensing - would love to devote. Even so, this Section will prove to be by far the longest in the Series. The intention is to provide a thumbnail view of the major missions to the planets but with the restriction that only surface images will be shown - usually no more than 2 or 3 representative of each mission. Despite the importance of learning about planetary atmospheres (Venus, Mars, the outer planets [Jupiter, Saturn, Uranus, and Neptune], and several satellites such as Neptune's Triton), we will not say much about the results of remote sensing of these gaseous envelopes.

There are many sources of additional images and descriptive information. Among the best of these currently online is a replication of Chapter 5: Planetary Geology, by James Bell, Bruce Campbell, and Mark Robinson, in the 3rd Edition of the Manual of Remote Sensing: Earth Sciences Volume, 1996 http://marswatch.tn.cornell.edu/rsm.html. This lengthy and detailed review is built around remote sensing approaches to planetary exploration. Its one drawback is a sparsity of images (compared with this Section 19 overview). Another site worth visiting is the general Home Page of the Jet Propulsion Laboratory (http://www.jpl.nasa.gov) where you can get addresses to visit other sites dealing with both terrestrial and planetary space programs. JPL has recently selected choice images of the planet from various missions in a special Web site called the Planetary Photojournal which is accessed on http://photojournal.wr.usgs.gov/. Some images used in this Section come from that source; others are resident there for your inspection. Another NASA source is the National Space Science Data Center (http://nssdc.gsfc.nasa.gov/image/planetary. Two other exceptional Home Pages are The Nine Planets, by Bill Arnett of the Lunar and Planetary Laboratory, University of Arizona (http://seds.lpl.arizona.edu/ nineplanets/nineplanets) and Views of the Solar System, by C.J..Hamilton of the Los Alamos National Laboratory (http://bang.lanl.gov/solarsys/). Books that offer extended treatment of planetary remote sensing include the aforementioned one by Billy Glass of the University of Delaware, and a now out-of-print text by this Tutorial's author (N.M. Short, Planetary Geology, 1975, Prentice-Hall Publ.), still in libraries. More recent are Planetary Landscapes by R. Greeley, 1985, Allen & Unwin, and Exploring the Planets by W.K. Hamblin and E.H. Christiansen, MacMillan, 1990.

Cosmology

Before we start our tour of the planets, you may wish to build a quick background in some of the main principles and concepts underlying astronomy. The writer has developed a synopsis of The Origin and Development of the Universe, emphasizing Cosmology, as part of an aborted textbook on Introductory Geology. This review is placed as a link for you to access if you so choose . While the synopsis is not really a remote sensing document, it is an efficient overview of several aspects of cosmic science that draw upon some of the same conceptions that underlie planetary science. Besides, the subject is incredibly fascinating and was great fun to prepare. But, be advised: I have put forth this distillation of the current views on Cosmology with some trepidation. The subject, with all its ramifications, is ever evolving, speculative, and still inexact in many aspects. I have written the review in a rather dogmatic prose, as though the topics are now almost "gospel", yet in fact I have played down some of the more exotic ideas (such as "multiverses" and "virtual creation"). These astounding notions will, however, be briefly treated towards the close.

Planetary Parameters

However, we will concentrate in this Section almost entirely on the planetlike bodies of the solar system (for information on the Sun itself, check http://seds.lpl.arizona.edu/nineplanets/nineplanets/sol.html and/or http://bang.lanl.gov/solarsys/sun.htm), excluding the Earth. To set a framework for our survey, look first at the illustration below which shows the relative sizes of the nine planets of this solar system (the distances between them are not to scale); using their appearance, how many can you name?

Then, consult the Table below which summarizes the principal characteristics and properties of the 9 planets (they are listed top to bottom in the same sequence as those shown from left to right in the above illustration). To simplify, names of the principal satellites orbiting some of these planets are not inserted in the Table but are covered in a listing below the Table proper.

PLANETARY BODY DISTANCE FROM SUN (AU) ORBITAL PERIOD (yrs) ROTATIONAL PERIOD (days) DIAMETER (km) DENSITY (gm/cm)3 NUMBER OF SATELLITES
Mercury 0.387 0.24 58.6 4880 5.44 0
Venus 0.723 0.62 243R 12105 5.25 0
Earth 1.000 1.00 1.00 12757 5.52 1
Mars 1.524 1.88 1.03 6786 3.93 2
Jupiter 5.203 11.86 0.41 143797 1.34 16
Saturn 9.539 29.46 0.43 120659 0.70 17
Uranus 19.18 84.01 0.72 51121 1.28 15
Neptune 30.07 164.80 0.73 49560 1.64 3
Pluto 39.44 247.68 6.4 2288 2.06 1
AU = mean distance (approx. 150 million kilometers; 93 million miles) from the Sun to the Earth

Names of Principal Satellites:

Table Of Contents [an error occurred while processing this directive] previous page [an error occurred while processing this directive] next page

Code 935, Goddard Space Flight Center, NASA
Written by: Nicholas M. Short, Sr. email: nmshort@epix.net
and
Jon Robinson email: Jon.W.Robinson.1@gsfc.nasa.gov
Webmaster: Bill Dickinson Jr. email: rstwebmaster@gsti.com
Web Production: Christiane Robinson, Terri Ho and Nannette Fekete
Updated: 1999.03.15.