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Armchair Astronaut
2009-Dec-19, 06:32 PM
http://img341.imageshack.us/img341/15/elongation.jpg (http://img341.imageshack.us/img341/9228/elongation.png)

I saw this kind of chart when I was a wee lad in one of my first astronomy books and found it extremely useful, but haven't seen anything like it ever since, so I thought I make one myself.

It plots the angle between each planet and the sun over ime projected to the ecliptic. So when you know where the
ecliptic is from your location (should be easy with every stellar chart/software), you can see immediately where each planet is along that line. When the track crosses the Sun-line at the center, the planet is at conjunction, when it crosses over from extreme left to right, the planet is at opposition.

What you see on the left half is the sky directly after sunset and on the right before sunrise. The visible sky window shifts between those two positions during the night at 15/hour. At least it does so when you are significantly outside of the polar circles, where sunrise/set behaves differently sometimes :) .

I also varied line thickness with apparent magnitude and included full-moon-markers on the right (or stay-home-markers for amateur astronomers ;) ).

If you miss Pluto, I made one with it here (http://armchairastronautics.blogspot.com/2009/12/elongation-charts.html).

I'm really not sure if the chart should be mirrored for a southern hemisphere POV or not. Can somebody clue me in?

hhEb09'1
2009-Dec-19, 06:38 PM
I saw this kind of chart when I was a wee lad in one of my first astronomy books and found it extremely useful, but haven't seen anything like it ever since, so I thought I make one myself.
Sky and Telescope includes one annually, except the times of sunrise and sunset are the left and right limits--it looks more like an hourglass. I'll see if I can find a copy.

Armchair Astronaut
2009-Dec-19, 11:58 PM
Ah, thanks.
Well, making it myself was more fun in any case.:lol:
And including sunrise/set makes it location-limited, of course.:whistle:

Romanus
2009-Dec-20, 03:49 PM
Ottewell's annual Astronomical Calendar always has an excellent one on the back cover. Of course, it's full of other goodies as well; you should get one. Now. ;)

Jens
2009-Dec-21, 03:53 AM
I'm really not sure if the chart should be mirrored for a southern hemisphere POV or not. Can somebody clue me in?

I'm not sure either, but I think it should, because the -45 means south in the northern hemisphere, but should mean north in the southern hemisphere. I also wonder how this would plot out at the equator, where the latitude can't become minus.

hhEb09'1
2009-Dec-21, 06:17 AM
And including sunrise/set makes it location-limited, of course.It took a while, but I found them here (http://www.shopatsky.com/products/U803.L1/Almanacs.htm). :)

Armchair Astronaut
2009-Dec-24, 09:50 AM
It took a while, but I found them here (http://www.shopatsky.com/products/U803.L1/Almanacs.htm). :)

Thanks. These things appear to be a lot more abundant in print than on the intertoobs. I've been looking at the wrong medium, it seems.

The charts you linked to look interesting. They are centered on midnght, exactly the opposite of mine, and therefore show the night sky in one piece. Makes sense, since that is what you're looking at most of the time.
OTOH that makes the interior planets clip in left and right, with no distinction between superior and inferior conjunction. Can have _everything_ in one chart, i guess.

Armchair Astronaut
2009-Dec-24, 09:58 AM
I'm not sure either, but I think it should, because the -45 means south in the northern hemisphere, but should mean north in the southern hemisphere. I also wonder how this would plot out at the equator, where the latitude can't become minus.

Maybe there's a misunderstanding, the degree-scale on my chart refers to angle between planet and sun, which is the same from any location on earth.

I was thinking along the lines that, since the constellations look the-other-way-up (I'm sure there's a proper term for it) from the southern hemisphere, this should apply to apparent planetary positions as well. I just can't figure out how, my brain gets all knotted up if I try.:confused: