Timescapes - Digital Timelapse Discussion
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Angle the sun moves at sunrise or set
http://forum.timescapes.org/phpBB3/viewtopic.php?f=4&t=12344
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Author:  Ian [ Fri Oct 24, 2014 11:28 am ]
Post subject:  Angle the sun moves at sunrise or set

Today I shot a timelapse of the sun setting between the towers of my local cathedral (St Gallen, Switzerland). When clipping the towers the partly concealed sun cast sharp beams (see link). But when the sun was totally unobstructed, the beams broadened and lost contrast. This got me to wondering - if I could find a mountainside that slopes at the same angle that the sun is setting (naturally the time of year makes a big difference), then I could shoot the sun riding down the slope as it were, casting sharp sun beams all the way. But how would I find out the angle at which the sun moves through the sky at any one given time and location? I know how to find out the angle of sunset as a compass bearing but not an angle as it pertains to the sun`s movement through the sky.
Thanks for your help.

PS I can`t upload the pic for some reason; keep getting a server error message (???)
So it`s here instead: https://www.facebook.com/photo.php?fbid=10152831859053103&set=a.10151946793678103.1073741827.524023102&type=1&theater

Author:  Tom Lapse [ Fri Oct 24, 2014 2:06 pm ]
Post subject:  Re: Angle the sun moves at sunrise or set

I can't access Facebook so I haven't seen your image, but a nifty little program called Stellarium (link below) might help you. Once you set the co-ordinates for your location, it shows everything in the sky in real time, and you can fast forward to see where everything will be later. I just looked at the sun setting in my location and it looks to be going down at about a 35 or 40 degree angle. Don't know if the exact angle can be determined, but I imagine it can be done.

It's open source so it's free, but best of all, it works. I've used it to see where the moon will rise and where the center of the Milky Way will be when the sun sets.

Hope that helps.

http://www.stellarium.org/en_CA/

Edit: There's a shot similar to what you're talking about in the trailer for Antz's awesome production, although it shows the moon going up a hill (backwards, but I assume that's because it's in the Southern Hemisphere?).

Link to thread with trailer: viewtopic.php?f=7&t=8951

Author:  Ian [ Fri Oct 24, 2014 11:49 pm ]
Post subject:  Re: Angle the sun moves at sunrise or set

Thank you Tom. I`d forgotten about Stellarium even though I have it on my computer! I shall stretch my brain and get to grips with it.

Author:  Tom Lapse [ Sat Oct 25, 2014 10:11 am ]
Post subject:  Re: Angle the sun moves at sunrise or set

You're welcome, Ian. It does take some brain stretching. I use it infrequently enough that I have to feel my way around it every time, but it has always come through. Hope it works for you.

Author:  Doggo [ Tue Dec 02, 2014 12:28 pm ]
Post subject:  Re: Angle the sun moves at sunrise or set

I use the iOS app called PhotoPills. It is seriously amazing, so many different features, one of which shows where in the horizon the sun/moon will be down to the minute.

Author:  jimre-temp [ Tue Dec 02, 2014 1:03 pm ]
Post subject:  Re: Angle the sun moves at sunrise or set

Star Walk is another good sky visualization app. I think they have versions for all the major smartphone platforms. Star Walk use your phone's camera to show an "augmented reality" view of the sky - superimposing celestial objects over the current live camera view, wherever you point the phone.

Relevant to your example, it superimposes the Ecliptic - the path of the Sun - as a dotted line over your live camera view.

Author:  sciencelookers [ Wed Dec 03, 2014 5:44 am ]
Post subject:  Re: Angle the sun moves at sunrise or set

The guys who came to film the turtles one Summer had an app like that on their phones. It would be really good for your purpose because it takes your GPS location into account. You can use it before setting up. You'll be able to see the path the sun will take from your exact location. It might tell you that you need to move slightly to get the mountain to line up with the sun's path. Picking a mountain with the right slope is only half the problem. Knowing where to stand to get the mountain and sun to align is just as important.

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