Pondering: enabling additional planets

[Mike V]

Eventually, I'd like to include toggles for the largest Solar System objects to optionally include them in charts. This post is about 3 related topics: which objects, what should their abbreviations be, and what format should the selections be in?

First, the question of which objects and what abbreviations. My thoughts are, going from largest to smallest:
Eris (already included) - Er
Haumea - Ha
Makemake - Mk
Gonggong - Go
Quaoar - Qu
----- Estimated diameter below 1,000km
Ceres (I don't personally have any interest in Ceres, but I feel like it deserves to be here) - Ce
Orcus - Or
Sedna (already included) - Se
Salacia (smallest named object in this class; ~850 km radius) - Sl

With just Eris and Sedna, the large toggles for each make sense, but this isn't possible with all of these extra bodies. I'm thinking of having a separate page that you navigate to from the Chart Options page. This just has a bunch of checkboxes, one for each planet, in a vertical strip.

This would take a bit of time to integrate, ultimately, as it would change the logic that is used to identify planets. The traditional astrological objects of Moon through Pluto go up in number from 0-9 (in terms of how the Swiss Ephemeris identifies them), but all the other objects are in the "asteroids" category, and have 6-digit designations. (I have most of them from work on my app, but I'd need to grab the rest.)

What do you think?

[Jim Eshelman]

Eventually, I'd like to include toggles for the largest Solar System objects to optionally include them in charts. This post is about 3 related topics: which objects, what should their abbreviations be, and what format should the selections be in?

All good questions.

For abbreviations, the ones you've used look fine. I don't think it's that big of a deal. Not a lot of people will probably tap these, but those who DO tap them can make easy sense of what you proposed, especially because the quantity of largest ones is small - and your suggestions are easily recognizable.

I'm currently thinking of splitting Classes 1/2/3 of planets (to use language, for a moment, that we use for nearly everything else) at 2,000 km and 200 km; but I recognize that we don't have anything really objective on the 1,000-2,000 km range, so this is hardly a settled definition. (I do like the 10x zoom, though.) I suggest we probably ignore anything under 200 km because, if nothing else, there are 200 asteroids in the 100-200 km range alone.

First, the question of which objects

Eris 2,326 km and Haumea 2,322 are the easiest calls. Quaoar and Makemake are in the 1,000-2,000 range and deserve inspection. I don't remember where Gonggong goes (I think I've only seen it mentioned in something you wrote), but I'm guessing it's in the 1k-2k range.

Since Sedna (995 km) is included, Ceres (954 km) surely should be; and Orcus is about the same size (917 km). And if we're going to cross the line into "Class 2" bodies, it seems we should include all the "original" (earliest found, largest, earliest used) "big four," which means adding Vesta, Pallas, and Juno. Chiron, barely above 200 km, should be included because of interest/popularity, the fact that it has shown recognizable results, and because it's pretty much in a class of its own as a body swinging between just inside Saturn and just outside Uranus. I have no idea what Salacia is but it doesn't particular standing among astrologers who are attentive to such things. (What "class" is it? You say it is the smallest in its class.)

With just Eris and Sedna, the large toggles for each make sense, but this isn't possible with all of these extra bodies. I'm thinking of having a separate page that you navigate to from the Chart Options page. This just has a bunch of checkboxes, one for each planet, in a vertical strip.

I like that. Makes sense.

Since quality ephemerides are available for hundreds or thousands of bodies, one day - TM 4.0? <g> - there could perhaps be a way for a user to import an ephemeris which adds the body to the selectable list.

[Mike V]

I'm currently thinking of splitting Classes 1/2/3 of planets (to use language, for a moment, that we use for nearly everything else) at 2,000 km and 200 km; but I recognize that we don't have anything really objective on the 1,000-2,000 km range, so this is hardly a settled definition. (I do like the 10x zoom, though.) I suggest we probably ignore anything under 200 km because, if nothing else, there are 200 asteroids in the 100-200 km range alone.

I actually love this way of thinking about it. To use the same terminology, I'm like 95% interested in Class 1 bodies and 5% interested in the rest... but I have a strong desire to find out if any bodies beyond the classic 10 are worthy of being considered "Class 1" and treated with the same consistent attention. That's my single largest motivation in this: check to see if there are any other Class 1 bodies. (We presume Eris is, naturally, and there's a strong case for Haumea just by virtue of its size - but what if there's more?)

Using diameter to distinguish between planetary importance is very natural, but I want to test the hypothesis that the smaller bodies do, in fact, generally just mean less to us than these larger ones - and where that cutoff (or cutoffs) might be. (Maybe it's in miles instead of kilometers ) I think the case of Chiron is an interesting point there; it's so small and yet has gotten what seems like worthwhile attention.

I suggest we probably ignore anything under 200 km because, if nothing else, there are 200 asteroids in the 100-200 km range alone.

I am extremely happy to ignore everything this size.

I don't remember where Gonggong goes (I think I've only seen it mentioned in something you wrote), but I'm guessing it's in the 1k-2k range.

1230 +/- 50km estimated radius, yes. It's (estimated) larger than Quaoar at 1086 +/- 2mk.

Since Sedna (995 km) is included, Ceres (954 km) surely should be; and Orcus is about the same size (917 km). And if we're going to cross the line into "Class 2" bodies, it seems we should include all the "original" (earliest found, largest, earliest used) "big four," which means adding Vesta, Pallas, and Juno.

That's fair. The Swiss Ephemeris allows us to calculate all of these, along with the thousands and thousands of other asteroids and TNOs - basically any object tracked by the Minor Planet Center (I think).

I have no idea what Salacia is but it doesn't particular standing among astrologers who are attentive to such things. (What "class" is it? You say it is the smallest in its class.)

I'm just going by the Wikipedia page, honestly. https://en.wikipedia.org/wiki/List_of_S ... ts_by_size

The "class" I mentioned here is "objects with radius over 400 km," or objects generally assumed to be capable of being in hydrostatic equilibrium.

The next lower designation is 200-400 km radius, where bodies are generally at least round, but they are definitely not in hydrostatic equilibrium (and TNOs in this range are expected to be very porous, not even fully solid bodies). Bodies in this size range include Vesta and Pallas, a bunch of moons, and some TNOs.

Since quality ephemerides are available for hundreds or thousands of bodies, one day - TM 4.0? <g> - there could perhaps be a way for a user to import an ephemeris which adds the body to the selectable list.

This is a cool idea. We'd have to have alternate code that doesn't use the Swiss Ephemeris for user-submitted files, but basically performs the calculation routines on them ourselves.

[Jim Eshelman]

Your answer suggests you haven't read the Intermediate and Expert sections of my Planets chapter of CSA (Chapter 7). For your probably interest, and to create common language, I suggest you grab that chapter and read the relevant (obvious at a glance) sections in the Intermediate and Advanced pages.

[Mike V]

Just read these and I'm caught up now.

[Jim Eshelman]

I added to the chapter a couple of more times, plus explicit diameters for a few of the list bodies.