The Dark Rings of Saturn

At the moment there is something interested going on with Saturn. The rings are very close to edge on at the moment and when like this the dark side of the rings can sometimes be observed.

Normally we look at the sunlit side of the rings for the obvious reason we are much closer to the sun than Saturn so we always see its illuminated face. However, when the rings are not angled to us it is sometimes possible that the relative positions of the Sun Earth and Saturn are such that we are looking at the the rings at such an angle we are seeing the unilluminated side and not the normally illuminated side. Such an occurence is happening now.


You can see this effect in DU by doing the following.

Run DU, open the find planet window and look for Saturn. Zoom in until you get a reasonable view of the planet and rings.

Open the Time Window and set the date to a few days ago on 2009/08/08 (in the DU YYY/MM/DD format). Then click the second tab and set the time advancement to 1 day. Then make sure you Lock onto the planet Saturn to keep it in view (BTW this last part will not be necessary in v1.7 as finding a planet will lock onto it automatically). Click Use to enable the time settings. Then advance the time by clicking the right cursor key (or you could use auto advance if you want).

Between the 9th and 10th August you will see the rings change to a dark colour as we are now looking at the shadow side, the sun in relation to Saturn and our line of sight (you obviously cannot see the Sun in this view BTW) has moved so that the other side of the rings has become the illuminated side. You will see that the rings remain dark until 3rd September when we are seeing the illuminated rings once more, which by then are extremely edge on.

@BillE

Thanks for the hint, cool view

Together with the Pleiides (sp?) lately it?s a really great month

Hi @BillE

Zoom in until you get a reasonable view of the planet and rings.
Zoom what?
Then make sure you Lock onto the planet Saturn to keep it in view
How do you 'lock' a planet?

@Snuffy

I suppose DU is a rather complex application and can be bewildering to people new to it - that is why I need and welcome feedback - so thanks for contacting me.


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You can zoom into the view in several ways - BTW - the HELP key works quite well with the Amiga Guide system. However there is quite a lot of the (RT)FM to read !

You can use the menus, shortcut RA [ and RA ] to change the field of view. You can open the Control Panel and enter any value for the field of view you want, there are also zoom_in and zoom_out buttons too. There are also several user defined fields that you can use by using 0 - 9 above the main keyboard (not on the numeric keypad).

However, the simplest way by far to zoom in to an object is to place the mouse over it, left click and then drag the mouse, you see a box defined that will then fill the screen when you release the mouse button.


Then make sure you Lock onto the planet Saturn to keep it in view
How do you 'lock' a planet?[/quote]

Fair question if you are new to using DU.

Open the Time Window fromt he menu or press RA T. Click the second tab or press F2. There you see three radio buttons, Lock Onto. Select "Object" and then you will get a list of objects you can keep fixed if you step backwards or forwards in time. As planets do move a lot against the starry backdrop you need to select one if you want to keep it in view. If not and you change the date you will find it has completely disappeared from view. Its like taking a movie of a racing car you have to keep the camera on the car and not the background


I hope this helps.


Bill.

@BillE

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That reminds me; some menu shortcuts are not necessarily so well chosen for those of us with non-English keyboards and/or Locale settings.

For instance, on my Danish PC keyboard, which I use on the A1, the square brackets are on the 8 and 9 keys in the main key section, requiring Alt Gr. So using them as menu shortcuts involves pressing Right Amiga together with the right Alt (Alt Gr) and the 8 or 9 key. Except that Right Amiga plus Right Alt also serve as the keyboard equivalent of the right mouse button! So that is not really possible.

(Luckily it is possible to substitute the left Alt key for the right one and press Right Amiga, Left Alt and 8/9; clumsy, but at least working.)

Best regards,

Niels

P.S. Oh yeah, thanks for the tip about the rings. Awesome display; wish I could see it directly. But Saturn is not visible from here, partly due to its low inclination (currently only above the horizon during the day) and the surrounding buildings and trees, partly because of all the light pollution. And (partly as a consequence of those conditions) I don't have any astro scope.

@nbache

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Could you send me a list of the ones that cause problems and I will see what I can do.

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I agree that is not really convenient. I only chose those key shortcuts as I looked around for applications that used zoom functions and had menu shortcuts and only found AmiPDF and AmiGS which both use RA with the square brackets, so I made the assumption that this was a (sort of) Amiga standard - or at least something people were used to for those functions.

I can quite easily change them, how about RA + and RA -. The plus key is awkward in the main keyboard section as it is shifted but the + and - in the numeric keypad should be the same for all keyboards.

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It is really too close to the sun for good viewing at the moment. It may be OK in equatorial regions where it darkens quickly after sunset but not for us in more temperate to polar latitudes.


Bill.

@BillE

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Will do; I'll try to get it to you together with the other stuff I'll be sending shortly.

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Hmm, I should probably nag Anthony about that. I didn't notice it before.

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Plus and minus would work fine at least on a Danish keyboard. Neither of them are shifted; minus is just to the left of the right shift key, and plus is just to the right of the zero key. I'm not sure where other national keyboards have them, but as you say, there's always the numeric keypad to fall back on.

Best regards,

Niels