Calendar event enumerator

[cosinekitty]

@matheo I have started a prototype of the calendar event enumerator as we discussed earlier. It is in the calendar2 branch. Take a look at calendar.ts.

The idea is that there are event enumerator classes you can create that follow a simple FindFirst/FindNext interface. Then you feed them into an EventCollator which merges the multiple event streams into one chronological stream. It does the minimum amount of work to iterate one event at a time, and uses only a small amount of memory. I think this would be a pretty good algorithm to feed a dynamic calendar inside a UI.

The example output is in calendar_correct.txt, which is a flat listing of sunrise, sunset, moonrise, moonset, season changes (equinoxes and solstices), and moon phases. I will add many more enumerators of interesting events soon (eclipses, conjunctions, etc).

I'll be interested to know what you think. Is this something you could build a calendar UI from?

[matheo]

Wooow yess!
seems enough data to build a nice UI :)
awesome stuff! thank you!

[cosinekitty]

OK, great! I will add some more enumerators in the calendar2 branch over the next few days. Basically I will add anything I can think of that I would personally want to see on an astronomy calendar.

[cosinekitty]

Tonight I added the following calendar enumerators:

• planetary conjunctions (when planets are invisible because of appearing too close to the Sun)
• planetary oppositions (when outer planets are closest to the Earth and best visible)
• max elongations of Mercury and Venus (when they appear at the largest angle from the Sun)
• Venus peak apparent magnitude (when Venus looks the brightest)

The remaining ideas on my list to be completed are:

• Lunar and solar eclipses
• Transits of Mercury and Venus (when they pass between the Sun and Earth)
• Lunar apogee and perigee (moon farthest and closest to Earth)
• Planet aphelion and perihelion (planet farthest and closest to the Sun)
• When planets enter a new constellation
• Moon and Sun culmination (time of highest angle above the horizon every day)

[matheo]

You can't imagine how badly I'd like to have your astro+math skills 😎
Thanks again for sharing them!

[cosinekitty]

Thanks, @matheo !

Tonight I finished lunar eclipses, solar eclipses, and transits of Mercury and Venus. I will continue working through the list I wrote above.

[cosinekitty]

I finished the calendar demo and it is now merged into the master branch. Its output is quite lengthy. For a real calendar, I suspect we would omit sunrise, sunset, moonrise, moonset, and Sun & Moon culmination events. If someone clicked on a particular calendar day, we could show all of those things, but for the overall calendar view, it would be a lot more efficient to only calculate events that don't happen every single day.

[matheo]

it would be a lot more efficient to only calculate events that don't happen every single day

I completely agree