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"Annulo cingitur tenui,
plano, nusquam cohaerente, ad elipticam inclinato"
"[Saturn] is surrounded by a thin flat ring, nowhere touching
and inclined to the elliptic"
Christiaan Huygens (1659)
Scary Saturn with Tele Vue Type B Mars filter
"Ring around the
rosie ... ♫"
as the old nursery song goes, Saturn is unique in that it is the only planet
visible from the small telescope. I can probably go out on the limb and rim and assert that anyone who has
looked at Saturn through a telescope is simply overtaken by its beauty. My NP127 and TV-102 Light Cup have
put together a collection of tips, guides, etc. to help new observers with Saturn using small telescopes (and
large telescopes too ). I seem to recall not to longer ago when I first started observing Saturn and could sure
enough see the ring. However, I couldn't even tell how many sub rings or the difference what they're or how the
"delicious" Crepe Ring look like through a small telescope.. I hope you find my Light Cup's collections useful as
I myself still have a life-long learning on The Ring Planet to do .
Galileo first turned his one-inch telescope on Saturn in
1610. His singlet refractor was not good enough to
resolve the ring but he made sketches. You can actually get this impression by using low power (no more
than 20x-30x) and defocus it. Saturn's appearance of "extra bodies" puzzled him and other astronomers
greatly for many, many years. Interestingly enough, Galileo made this sketch and sure look like a ring to us
modern observers. Although even small kids know today that Saturn has rings, we must try hard to remember
that in the 17th century, the conclusion was not at all obvious. Huygens finally figured it out in 1657 using
maginification of 50x (see above latin quotation) and made a sketch. Despite his painstaking observation,
his ring theory (as it was called at the time) was met with attacks (sounds familiar today ) by other
astronomers of his time. And Cassini was able to determine in 1676 that there is a dark gap in the ring
which is known today as the "Cassini's Division".
This historical tidbit serves to underscore the
thought-provoking observation by Dr. Julius Benton of the ALPO
when he wrote "...it is important never to forget the important lesson that what we interpret from observations
does not depend soley on the quality of the telescope being used, but also on what we may expect to see at
the eyepiece in connection with existing theories at any given time."
Superficially, Saturn is a fairly
easy object to observe
(unlike Mars). However, just like anything skin deep
there are more than meet the eye. Saturn can be a very difficult planet to extract details and changes from a
small telescope! The crux of the matter is that Saturn's globe is never much larger than 20 arcsec in size
(roughly the maximum size of Mars during its 2005 apparition). Its rings span a maximum size of 46 arcsec
and give us the illusion that the planet is much larger . Often, beginners like me , make mistakes of
starting our observation when Saturn is too low over the horizon and be disappointed by pulsating/vibrating/
yo-yo featureless yellow blob. On one night, the seeing was so bad that I could not see the Cassini's Division
at any magnification; luckily, I could still make out the ring . Try to observe Saturn when it is at least 45º
above horizon or higher.
sure your optics is clean, collimated and cooled down. Unlike large light bucket, use as much
magnification as supported by your optics and the seeing condition with your small telescopes. In my
opinion, the 30X/inch "optimum rule" does not apply for small telescope with good optics. With average
to excellent seeing condition, Saturn can take as much as 44X to 75X per inch in my 4-inch Light Cup!
Therefore, because Saturn is a small disk at best, start with at least 150x (more if seeing permit). Be patient
at the eyepiece and you may have to wait for fleeting moments of clarity. If you don't have driven mount, a
wide FOV eyepiece can be very helpful and avoid having to nudge so much. An observing chair that allows
you to sit down may add a "virtual one inch" to your small telescope ! Try to make a sketch; sketching will
help you to focus and therefore help you to see more details.
So what should you be looking for? Well through a
small telescope, such as my 4-inch TV-102 Light Cup
I can make out the ring at only 20x-30x. The Cassini's Division is obvious at around 70x. Look for Ring A,
B and C (also called Crepe Ring). Ring A is narrower and dimmer than B. The Crepe Ring can be very
elusive through a small telescope because it isn't very bright, especially now that Saturn's rings are now
not opened nearly as wide as last year. It is easier to see the Crepe Ring when it crosses in front of the
planet and around both ansae. With 175x-200x or more, look more low contrast shading in Ring B and a
#8 or #12 filter may help. Also, keep a look out for 'em spokes (although I've yet to see it ). Look carefully
and you'll notice that Ring A is not as solid as Ring B looking like it's made of a "set of wires" (minimas)
through my Light Cup.
Look for shadow of the globe on the ring at around 150x.
The best time that Saturn will cast the maximum
amount of shadow on the rings is at quadrature, the time when the planet forms a 90° angle between our
earth and the sun. This occurs at the time when Saturn rises at midnight; so early bird morning hours before
sun rise is best. Look also for shadow of rings on the planet's globe. You'll get another opportunity after
opposition when Saturn is high overhead at sunset; note the shadow is now on the opposition side! When
the ring is widely opened, you may be able to see the globe through the Cassini's Division!
Check out the bicolored aspect of the rings first
noted by Walter Haas, that is, one of the ansa of the ring
is brighter than the other! To help identify this aspect, use color filters starting with #47 (not for small
telescope), and work your way through the filters with #80A, #58, #12, #21, #25 (not for small aperture)
and note which side appear brightest with each filter.
If you look closely, the belts and bands on the planet's
surface is similar to those on Jupiter. Try to use
between 150x-200x at least to making out the belts and bands on the planet's surface. The EB can be
quite a torture to make out. I've found that a #8 or #12 yellow filter can help in bringing out the contrast.
Although not a frequent occurrence, look for festoon. Take note of the various different colors in the belt
especially the olive green SPR which is obvious through my 8-inch Dob and easy through my 5-inch NP127
Light Cup and can look dark gray/brownish in smaller telescopes. Throughout history, there have been
reports of spots in various part of the planet. During the 1990's, the spectacular "Great White Spot" erupted
on Saturn. Have a look at this spectacular movie . There's also a special kind of spot called the "Terby's
White Spot" which is actually an optical illusion ; the #12 yellow filter can be useful.
Many Saturn's satellites can be seen through a small
telescope. For a telescope of 4-inch aperture, Titan
(mag 8.2), Iapentus (mag 10.2-11.9), Rhea (mag 9.7), Dione (mag 10.4), Tethys (mag 10.2). Enceladus
(mag 11.7) can perhaps be seen with difficulty only when it is at its largest elongation. My Light Cup
considered Mimas (mag 12.9), a 4-incher "holy grail" . And like the Jovian moons, you can also see
them "dance" around Saturn (though not as rapid as the Jovian ones). Satellite transit and occulation
occur when the rings appear edgewise. Only Titan can cast shadow visible through small telescope.
Beware that it is difficult to see because the shadows are so small. In 2006, Titan reaches 0.88" in
apparent size. So you who have a 6-inch and larger telescope may wish to pile on Powermates or
your favorite Barlow to see if you can see it as disc.
An interesting and rare event is Saturn's occultation of a star,
especially a bright star. On Feb. 9th 1917,
a historic passage of the 7th magnitude star, BD +21 1714 behind Ring A that proved the translucency of
Ring A and final proof of Cassini's Division being a true gap. John Knight used a refractor as small as
5-inch at 100x, 180x and 250x. Here is a spectacular sketch of occultation of 28 Sagitarri in 1989.
Fortunately for me, I was able to witness the occultation of SAO 78867 on 11/15/03. See this jaw drop-
ping movie of the occultation.
Observing the Ring Planet is a
long-term proposition. It takes 29 years for the planet to go
complete cycle and ring tilt. Have a look at this cool (QuickTime) animation . In 2003, I was very
fortunate to communicate with Walter Haas, one of the greatest observers of our century and the founder
of the ALPO. He told me that he first looked at Saturn in 1933 and he is currently going through his Saturn's
third passage!!! That's a WOW-WOW ! After that, I realized for the first time that unlike DSO,
planetary observation can take a very long time to go through just one complete cycle and just to see it
with a different perspective for the apparition, let alone three passages! Personally for me and my Light
Cup, we look forward to my first ring crossing in 2009 .
Finally, here you'll find useful information and links my
Light Cup has brewed together to help us newbie
and oldie alike to observe Saturn.
Saturn Tours Guide
2006 Focus on Saturn by Skyhound
ALPO Saturn Section
Saturn ALPO's Recommendation
Activities on Saturn
Guide to observing Saturn
S&T Saturn's Observing Guide
Descriptive View of the Planet Saturn
Rings of Saturn
Lord of the Rings
De-confuse the confusing Rings
Spokes of Saturn
Changing Color of Saturn
Saturn Survival Tool - The Planets (a MUST HAVE)
S&T Saturn's Moons Predictor
Saturn's Current Moons Position
Which filter to buy for Saturn
Saturn vs Earth
Titan vs Earth
Let History be our Teacher - learn about
Brief History of Saturn's Observation
Brief History of Saturn's Observation (1600's)
Historical Background of Saturn's Ring.
Huygen's Systema Saturnium (beware you'll need brush up on your high-school/college latin )
Link to Photos & Sketches
Saturn 2006 images through non-other than the 5-inch Tall Light Cup
Amazing color Saturn photo by Charles Capen back in 1966!
Saturn's image through the 4-inch TV-102 Light Cup
Photo of Saturn through a 4-inch Vixen 102FL
Saturn Photo through a 4-inch Takahashi FS102
Saturn through 5-inch Takahashi FS128
Hubble's Photo of Saturn Lunar Shadow Transit
Sketches by Sol Robbins
Sketch of Saturn Lunar Shadow Transit
It appears that there are lots of book on Saturn dealing with the planet itself and space exploration but not many
current books on how to observe the planet with a ground telescope. Here is a list on a few.
Saturn and How to
by Julius Benton (new book for 2005).
Best modern Saturn observing/imaging book - a MUST HAVE
Observing and Photographing the Solar System by Dobbins, Parker and Capen. Chapter 7.
A Complete Manual of Amateur Astronomy by Sherrod & Koed. Chapter 8.
The Planet Observer's Handbook by Price. Chapter 10.
the 4-inch/5-inch Tall Evangelist
EB = Equatorial Belt, EZ = Equatorial Zone, SEB =
South Equatorial Belt, STrZ = South Tropical Zone
STB = South Temperate Belt, SPR = South Polar Region