How do I calculate sunrise/sunset times for non-Earth planets?

[Gidde]

I think your best bet is most likely Celestia (it's free, and it's awesome -- http://www.shatters.net/celestia/). What it does is allow you to create a custom star system with the variables you mention, plus a few others, and then models it for you so that you can see exactly what it looks like. You can find some great tutorials at http://www.celestiamotherlode.net/ca...mentation.html -- I'd start with the Introduction to Celestia Add-ons by Selden Ball, Jr. It goes through the process of creating a fictional star system. From there you'll know which tuts to look for.

As for whether you're mad to consider this level of detail: I've done it, so if you're mad so am I! Also consider that (arguably) what made Tolkien great was the insane amount of detail he put into his fictional world. So as far as I'm concerned, you're making it better with each detail.

[snoopy]

I think your best bet is most likely Celestia (it's free, and it's awesome -- http://www.shatters.net/celestia/). What it does is allow you to create a custom star system with the variables you mention, plus a few others, and then models it for you so that you can see exactly what it looks like. You can find some great tutorials at http://www.celestiamotherlode.net/ca...mentation.html -- I'd start with the Introduction to Celestia Add-ons by Selden Ball, Jr. It goes through the process of creating a fictional star system. From there you'll know which tuts to look for.

As for whether you're mad to consider this level of detail: I've done it, so if you're mad so am I! Also consider that (arguably) what made Tolkien great was the insane amount of detail he put into his fictional world. So as far as I'm concerned, you're making it better with each detail.

I took a look at it, but I think I prefer Space Engine. It's free too, and from what I've seen of what can be done in Celestia, even more awesome. More types of navigation controls, and most importantly, in addition to known celestial objects, Space Engine populates the rest of the universe with procedurally generated ones. As in millions of galaxies with trillions of star systems to explore. And you can land on all of the planets, stars, moons, etc. and explore the procedural terrains. It also allows you to create and import your own stars, planets, etc. with orbits defined by those parameters. I've actually got the two stars done and orbiting properly. No planets yet though.

Here's the link, if you don't know about this program yet: http://en.spaceengine.org/. If your computer can run it (it has rather high requirements), it's about the best thing you'll ever download.

But what these programs can't do that I know of is tell me the time of sunrise and sunset at a given location on a given date. The closest I could get was focusing on a particular longitude and latitude on a planet and watching the day/night boundary go by in Celestia. That's a bit cumbersome and imprecise unfortunately. What I really need is something like the Navy link I posted, something that will output charts with dates and times.

That Celestia tutorial had some nice links to information on orbital elements, by the way.

And yes, I completely agree about Tolkien. It might be that I am nerdy enough to be most of the way through the History of Middle-Earth books... Learning enough about linguistics and philology to create a good language might take me a while though. One thing at a time.

Lastly, you said you've done high detail work: Did you attempt anything similar? If so, how did you handle it?

i asked if there was any interest in such a program a month or so ago.. this is the only positive comment i've seen yet.

even without a script, you ought to be able to get there with some basic trig. if you want to write something and get involved, all the data is out there of course.. perhaps the henon oscillator model would allow you to feel sufficiently technically involved

I would most definitely be interested. It's a shame (if an unsurprising one) that there hasn't been any other interest. And that basic trig is one thing I'm hoping to learn, since I don't know how to apply it to this problem at the moment. Sadly, I lack the expertise to program anything, so I doubt I could turn it into automated form even after I learn the math.

[xoxos]

I would most definitely be interested. It's a shame (if an unsurprising one) that there hasn't been any other interest. And that basic trig is one thing I'm hoping to learn, since I don't know how to apply it to this problem at the moment. Sadly, I lack the expertise to program anything, so I doubt I could turn it into automated form even after I learn the math.

tbh i think it would be fastest to blag it with a sine. take the sine of the date as a % of the year and set your minimum and maximum for summer and winter. you'd be close enough just to linear fade between them.

[snoopy]

I have actually found a fair amount on the way it is calculated on Earth now. I still have to read more to understand it, but I think I have at least figured out how to use novel time scales, which is to define them in terms of angle. 1 hour on Earth (a sidereal hour) is equivalent 15 degrees around the axis of rotation. You can simply redefine an hour in terms of the number of degrees out of 360 the planet rotates in that time period. If you know the angular velocity of its rotation, then I think it should be easy to use this value in the 'normal' Earth equations.

This is very useful: http://en.wikipedia.org/wiki/Sunrise_equation

I should have known to go to Wikipedia first.