Saturn Section

Mission Statement

The A.L.P.O. Saturn Section

Secondary in size only to Jupiter, the planet Saturn lies at 
a mean distance from the Sun of some 9.5 AU 
(astronomical units). Considered only as a globe, the 
planet is a somewhat smaller, dimmer, and relatively 
quiescent replica of the giant Jupiter. With its majestic and 
symmetrical ring system, together with the brighter eight 
satellites accessible to moderate-size telescopes, Saturn 
emerges as an object of exquisite and unsurpassed 
beauty, holding a particular magnetism for the visual and 
photographic observer alike. Besides its aesthetic 
qualities, Saturn exhibits numerous features requiring 
persistent and meticulous observation. At opposition, the 
globe of Saturn subtends an angle of about 17" (seconds 
of arc) in equatorial diameter, while the ring system's 
major axis spans nearly 42". Those experienced at 
observing Jupiter will note that Saturn requires almost 
twice the magnification needed for the Giant Planet so that 
a disc of comparable proportions is produced. In addition, 
those with relatively small telescopes will frequently find 
that Saturn is relatively barren and changeless, seldom 
displaying the wealth of activity that is so common on 

It is quite hazardous to try to establish some inflexible 
minimum with respect to aperture, particularly when it is 
recalled that extraordinary results have been obtained in 
past years by experienced observers using extremely 
small instruments. Almost any optical assistance will show 
Saturn's spectacular ring system, and the major disc 
features are revealed with a 7.5cm. (3.0in.) refractor, 
including perhaps a major belt and a zone or two near the 
equator of the planet. Cassini's Division should also be 
visible in the rings with such an instrument. Moving up to a 
10.2cm. (4.0in.) refractor or a 15.2cm. (6.0in.) reflector, 
the observer will discover that he has found about the 
minimum aperture that will prove to be suitable for routine 
and beginning detailed studies of Saturn. Of course, when 
seeing and transparency conditions allow, the larger the 
aperture, the bigger will be the image scale and the 
greater the resolution and image brightness. Experienced 
observers have found that a 15.2cm. (6.0in.) refractor or a 
25.4cm. (10.0in.) reflector is an ideal instrument for 
observing Saturn. More important than instrument design 
is optical and mechanical quality, and the prospective 
Saturn observer should obtain the best telescope he can 
afford. Excellent optics and a stable mounting are of far 
greater importance that sophistication of electronics in the 
mounting or exotic substrates or coatings for the lenses or 
mirrors. Some observers in recent years, for example, 
have successfully used simple, but premium-quality, 
Dobsonian reflectors when observing Saturn. The novice 
should spend some time in experimental work with the 
telescope he intends to use for following Saturn, seeking 
to establish the best combination of magnification, filters, 
and image size, brightness, and contrast. These topics, 
and many others, are discussed in considerable detail in 
The Saturn Handbook. After a bit of experience in 
observing Saturn, individuals will want to become familiar 
with the more advanced methods and techniques 
described in that book.

Like Jupiter, Saturn displays in an appropriate telescope a 
series of bright zones and darker belts that run roughly 
parallel to the equator. Much of the fundamental 
nomenclature assigned to the specific zones and belts of 
Jupiter applies to Saturn. The Saturn Handbook gives more
detail on the specialized uses of all of the terminology 
and nomenclature for Saturn.

Observations of the Saturn's globe, rings, and satellites 
are organized into the following routine programs:

1. Visual numerical relative intensity estimates of belts, 
zones, and ring components.

2. Full-disc drawings and sectional sketches of global and 
ring phenomena (the Saturn Section furnishes templates 
with the correct global oblateness and ring geometry to 
facilitate drawing). All drawings submitted for publication 
must be originals, not xerox copies.

3. Central meridian (CM) transit timings of details in belts 
and zones on the globe of Saturn (utilized to deterimine or 
confirm rotation rates in various latitudes).

4. Latitude estimates or filar micrometer measurements of 
belts and zones on the globe of Saturn.

5. Colorimetry and absolute color estimates of globe and 
ring features.

6. Observation of "intensity minima" in the rings (in 
addition to observations of Cassini's and Encke's 

7. Observational monitoring of the bicolored aspect of the 
rings of Saturn.

8. Observations of stellar occultations by Saturn's rings.

9. Specialized observations of Saturn during edgewise ring 
presentations in addition to routine studies.

10. Visual observations and magnitude estimates of the 
satellites of Saturn.

11. Routine photography, CCD imaging, photoelectric 
photometry, and videography of Saturn and its ring 

12. Simultaneous observations of Saturn.

Individuals interested in participating in the A.L.P.O. 
Saturn programs should contact:

Julius L. Benton, Jr.
Associates in Astronomy
P.O. Box 30545
Wilmington Island
Savannah, GA 31410

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