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Good Morning Jupiter

by Richard Orr, a customer of C-7 who owns an Astro-Physics 155mm EDF.

Used by permission of the author, this appeared in Oct. 1998 "Mason-Dixon Astronomer"
newsletter of the Westminster Astronomical Society of Maryland.

The full moon radiated painful light against the clear sky. At three in the morning the proud owners of those huge light buckets were fast asleep dreaming of clear moon less nights. With them seemed to sleep the rest of the world. Only my telescope and Jupiter kept me company -- no distractions -- just the three of us until dawn.

Festoons, garlands, ovals and rafts. How I have missed Jupiter. For the first time this year the "King of the gods" is getting high enough for me to observe it from the wooden deck behind the house. My love affair with Jupiter started back in 1959 when I turned my newly unpacked 60 mm refractor on the brightest "star" that I could find from my parent's backyard. When Jupiter popped into focus with its oblate disk, two distinctive equatorial cloud belts, framed with two Galilean moons on each side, I was spell bound. I had no idea what it was. But my father did -- back then my dad knew everything.

I can still get an observational rush when the air is steady and Jupiter is high in the southern sky. It's face is forever changing. This morning the sky was stable and clear and once the 155mm refractor was pointed on Jupiter, the high intensity moonshine was soon forgotten. Like my first Jupiter night in 1959, I had two moons on each side of the planet. Callisto and Io to the west and Europa and Ganymede to the east. Adding a nice touch was a field star shining at the same magnitude as the moons just north of the planet's disk.

The amateur planetary observer is currently in the minority in this hobby. More and more the planets seem only to rate quick glimpses at star parties (Wow, Saturn is pretty tonight -- if you stare at it for 15 to 20 seconds you can actually see the shadow on the rings and the Cassini division -- oh look! Is that Titan? -- yes but I've seen that -- lets look at NGC #$@X).

Ok, I am being a bit unfair, but for whatever reason the art of planetary observation is not being communicated well to beginning amateurs. Unfortunately, many come to the telescope with the preconceived idea that they will see a CCD enhanced Jupiter. The images (both from amateur and professional telescopes) that exist in books and magazines are artificially enhanced to exaggerate contrast. These are false images in the sense that no matter how close you were to Jupiter, or no matter how big your telescope was, this is not what you would see with your eyes.

Many amateurs unfairly blame their telescopes when Jupiter refuses to expose its subtle surface details. How many times have you heard, "I need an apochromatic refractor or a long focal length Newtonian reflector to seriously observe the planets". This kind of talk is justified only if you are trying to sell apochromatic refractors. Do not get me wrong, I love my apo and for ME it is the telescope that best fits my life style. But the truth is, regardless of the make of your telescope if it does well on a star test it will do well on the planets.

Although there are real differences in performance between different types of telescopes -- they are subtle. The most important overall basic ingredient for planetary viewing is optical quality. Light gathering ability (bigger is better) and contrast (more is better) are also important but optical quality wins out as the backbone of planetary observing. The planets, more than any other celestial object (including double stars), are the most unforgiving of poor optics. In today's market, any telescope which does not do well on a star test should be returned. If your telescope is not doing well on Jupiter it is not doing well on anything.

Real time visual observational details comes with practice and patience. The majority of detail on Jupiter is subtle -- you will not see it immediately. You have to take your time; see which eyepiece works best and resist using higher powers than the telescope / atmosphere will accept.

When you plan on observing Jupiter schedule at least 1 hour. Better yet schedule two and make a drawing. On some nights the detail that you are seeking will only appear intermittently when the atmosphere steadies -- be willing to wait. Be comfortable. Use your clock drive and sit down. The details you are after, especially at higher powers, will not come if you are uncomfortable or constantly having to adjust the scope. A little preparation before hand to insure that your polar alignment is good and that the eyepiece, and your eye, are at a comfortable position will make all the difference in the world. Jupiter makes you earn views of its surface markings.

I have always found Jupiter a challenge to draw. If the night is kind, Jupiter can show an enormous amount of detail. This in itself would not be a problem except that Jupiter rotates in just under 10 hours. Capturing the detail in a drawing for the entire disk before the far edge rotates out of view and new detail emerges from the opposite edge is not easy. I get around this by drawing a quick (1/2 hour) drawing of the entire disk and then finish with enlarged sectional sketches of specific areas of interest taking as much time as necessary. This morning my whole planet drawing was done at 218x (10mm Zeiss Orthoscopic, w/Barlow, no filter) and sectional sketches at 362x (6mm Zeiss Orthoscopic, w/Barlow, blue, green, and orange filters).

The North Equatorial Belt was thinner but darker than the South Equatorial Belt. The north polar shading was much more extensive than the south polar shading and seemed to flow into the location of the North Temperate Belt. The southern edge of the North Equatorial Belt was irregular with a number of dark projections and a large pale oval or garland extending into the Equatorial Zone. The Great Red Spot, which was floating on the southern edge of the South Equatorial Belt, was very pale with no discernible color, but the Great Red Spot Hollow was very distinct with a number of dark concentrations. Along the far edge of the Great Red Spot Hollow was a massive white patch followed by a smaller pale patch probably marking the leading edge of the South Tropical Disturbance.

I was not able to find the consolidation of the two white ovals in the Southern Temperate Belt which is the talk of Jupiter observers everywhere. These ovals (three of them) have been around since 1939 and have recently bunched together. Based on the Hubble Space Telescope images which showed the ovals' internal wind direction, scientists thought that the ovals would not fuse but just roll past each other. Apparently they were wrong, and two of the three ovals have merged. Since I was not able to see a full rotation of Jupiter's surface I am assuming that the consolidated oval never came into view. Maybe, or maybe I just missed it. But Jupiter is back and it will give me many a chance to test my skill and patience in the months ahead.

Never pass up a clear sky.

Richard L. Orr
11 - July - 1998


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