# How can I calculate the sun rising time for a specific point on earth?

I'm looking for a tool, application, etc. that allows me to calculate the sun rising time for any specific point on the earth. I've found a lot of such tools, but all of them do not take mountains, etc. into account that will block the sun. To clarify: I'm interested in the time when I'll be able to see the sun.

I'm asking this, because when traveling I like to take pictures during sunrise.

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Off-Topic: I have a piece of code written in c to calculate this. I remember converting it to C#. You will need longitude, latitude and elevation to get the time. Let me know if you need it and I will find it for you. – Heidel Ber Gensis Oct 19 '12 at 9:29
Cool! I'm also looking for an equation or code ;) – RoflcoptrException Oct 19 '12 at 9:31
@HaLaBi: Did you actually manage to implement it in a way that accounts for nearby mountains blocking the sun? It would certainly possible, given detailed enough geo data and there are public APIs you could get it from, but still complicate the calculation enormously. – Michael Borgwardt Oct 19 '12 at 9:43
@MichaelBorgwardt I did not notice the mountains thing.. I guess I read it too quick.. offcourse my code does not calculate the mountains and stuff.. it just calculates the normal sunrise time.. – Heidel Ber Gensis Oct 19 '12 at 9:51
@mouviciel I'm not sure if this is practical. For example for my village I couldn't answer this question even for a single point. Additionally, it is not always easy to first find a locale. And the sun rise time changes every day, so it would be difficult to get reliable information. – RoflcoptrException Oct 19 '12 at 11:27

Google Earth can do this. Click on the Sun-icon and draw the slider around until you see the sun rising:

Example is from Google Earth 6.0.3.2197.

This is mainly suitable if you need only one place and time, not if you need full tables of many places and times. Also, of course, in mountainous areas the answer is extremely local, but no tool can give you an answer on a meter-precision, so unless you have a highly detailed digital elevation model, Google Earth is probably the most accurate you can get.

Otherwise, you might want to ask over at GIS Stack Exchange.

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Note that you will estimate the time of sunrise too early if you don't stick the camera to the ground, and I haven't tested the accuracy. I'd be interested to hear some feedback as to whether this actually works well in practice. – gerrit Oct 19 '12 at 15:30

Can I suggest Stellarium, which is a free planetarium program available for Mac OS, Windows and linux.

For any date, time and geographical location, you can obtain sunrise time and position.

To take account of mountains etc, there is the added option of including into Stellarium a horizon image. This will give you an idea of how mountains etc may affect sunrise time.

I rather think, however, that including a horizon image into stellarium might well be more effort than you intend to exert!

As a rough and ready estimation of the angle subtended by a mountain, estimate as follows from here:

You can estimate altitudes by extending your right arm in front of you, at eye level, with the hand bent toward you, and turned so that the palm and fingers are extended horizontally to your left. With the thumb held next to the fingers, so that all five digits are close together, the width of the hand is about 10 degrees. If you have a narrow hand, or a long arm, your hand may only cover 9 degrees, and a wide hand, or a short arm, may cause your hand to cover 11 degrees; but there isn't generally much more variation than this.

You can then use the sun altitude data from stellarium to estimate when the sun will appear over the mountain. You might also need a compass to orient yourself and your observations.

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The Photographer's Ephemeris is the one that I use. It's quite practical and is an Adobe Air application.

I use it for the same reason that you mentioned and it hasn't failed yet no matter where I was.

It's available for iPhone, iPad, iPod Touch, Android system, Windows and Mac.

Desktop version are free but you do have to pay 5\$ (Android) or 9\$ (iOS) for mobile apps.

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All these graphical tools are very nice, but you can simply go to Time and Date on the internet. There under Sun and Moon you can check for any time. For example, to see the November 2012 times for Vancouver.

Another way is to look at the weather on Wunderground. For example, the forecast for Vancouver shows the sunrise and sunset times.

Naturally this doesn't necessarily take in the mountains, but if you know there aren't any then this is a quicker way.

Failing that, I use terrain data in Google Earth, which is what we did to calculate where the eclipse would be in El Calafate, back in 2010. The eclipse was like 0.5 deg above the mountains, so we had to have it between the right mountains and be up a hill ourselves, to avoid having them block it. It was touch and go, for sure!

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