How can I predict the moon's location?

I was looking out my window this morning and the almost full moon was setting very close to my view of the Detroit skyline. It would have made a great picture if the moon was just a little to the right - also if I had my camera with me.

How can I find out what time and on what day the moon will appear in the sweet spot so I can bring my camera in on that day? Do I need an astrolabe and a degree in calculuus? Is there a web site? a program I can download?

This might be what you need.

The moon’s a day after full this morning, so it set about 50 minutes after sunrise. Your next chance for a similar view will occur when the moon is next a day after full; november 16th.

Awesome! What a cool tool.

Now, to find one that does the reverse: lets me enter alt/azimuth info to calculate date/time…

Awesome! What a cool tool.

Now, to find one that does the reverse: lets me enter alt/azimuth info to calculate date/time…

Well, just ask for the azimuth at the full moon nearest the winter solstice, and the full moon nearest the summer solstice, and then home in on the azimuth you need.

For example, for my location the moon is at azimuth 303 at moonset on December 17, 2005. It’s at azimuth 232 at moonset on June 12, 2006. So, if I wanted azimuth 275, I’d guess that’d be about half way, so it could be somewhere like March or April’s full moon.

Note also that the moon moves pretty quickly from day to day, so for example on March 12, 2006, the moon sets at azimuth 275 and is 100% full, but the next morning it sets at azimuth 268, and the following morning at 262 when it is “only” 98% full. The moon also moves horizontally as it sets, so for example if it sets at 7:00 AM on March 14 at azimuth 262, 20 minutes earlier it is at azimuth 259.

Finally, it’s probably easier to adjust the azimuth of Detroit for yourself by driving north or south a small distance.

Figure out the azimuth of the moonset on a particular day, then drive until your compass indicates (don’t forget declination!) that azimuth as pointing right where you want it on the skyline. I bet a GPS with the right software would make this super easy.

Sky & Telescope’s Interactive Sky Chart
You can enter your location, then enter the date and time of the last full moon. Then center your view on the moon rising for that time and date. Then incrementally add one full day per click (or better yet click and hold on mouse and move mouse to add days rapidly). This will adjust the moons position one full day and then you can “scan” for the next full moon and its location relative to your “favorite position” that you saw a couple of nights ago…pretty cool tool for free, and fun to toy with. Enjoy.

You kids and your new-fangled “computers”!

In the old days we used to be able to predict the moon’s location using nothing but a bunch of stones!


This is the science teacher in me, but you COULD observe the moon for a month or so. I’ve had students (from 5th grade through graduate school) do a moon journal, recording their observations of the appearance and location of the moon on a daily basis (idea stolen from Eleanor Duckworth). Pooling the observations in a few class sessions at the end of a cycle causes a large number of "Ahhh, I get it"s and "Oh, now I see"s. In fact, it wasn’t until I did one of my own that I gained the perspective and understanding that I needed in order to teach it adequately. According to some statistics that I recently made up, under 5 percent of adults can correctly describe the motions of the moon, explain its phases, and predict its location for, say, a particular time of day one week ahead. For instance, most people don’t realize that one can see the moon some time of the 24 hour day EVERY day of the month, minus about two days. If you can take the time and discipline necessary, I guarantee you an astonishing self-education on this one. xo, C.

Now CC why didn’t you raise this excellent activity back in this thread :D?

Seriously, this is a great idea… something Nature Boy and I will start tonight!

I would if I could, but I’m at work. The boss probably wouldn’t miss me too much if I truck off to snap the pic, but the view I’m looking at is from the 3rd floor of the building. The angle is destroyed when I hop in the car.

I brought my camera in today hoping the moon woulda scooched a bit in - or take the pic nonetheless. But about an hour before M-time, a glut of clouds rushed in and parked right over the moon. Bummer. Maybe tomorrow…(checks astrolabe)

Mainly because of what I said - that the joy of science and discovery comes from within, even if it sometimes is goosed just a little by suggestion, modeling, and other subtle forms of motivation. But when it’s a Mom and Pop initiated or organized activity, it becomes something entirely different. And, it looks like someone’s going to have to do it tonight because a parent thinks it’s a great idea. That’s why I didn’t mention it. It’s contrary to my beliefs about learning, science, education, child-rearing, etc. Not to put too fine a point on it.