Talk:65489 Ceto

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Dwarf planet

Mike Brown's GENERIC website claims everything from 200 to 400km is *possibly* a dwarf planet. Obviously anything less than ~250km in diameter is not likely to qualify as a proper dwarf planet. -- Kheider (talk) 21:26, 3 October 2015 (UTC)[reply]

How do you know that? At just 213 km, Phoebe once was round. --JorisvS (talk) 22:44, 3 October 2015 (UTC)[reply]

Is that 200-400km diameter, or radius? There seems to be a bad habit around here of giving a "size" for minor planets without specifying which it is, with the figure then being reinterpreted arbitrarily elsewhere as one or the other... which of course means a potential 2x discrepancy in stated sizes, or even 4x with a diameter wrongly taken as radius vs the opposite case.

From what I've been able to interpret so far, it seems that this should be *radius*... as looks unlikely anything below 200km radius / 400km diameter has any chance of being considered a dwarf planet, as it simply wouldn't have enough mass for any common constituent material to undergo graviational rounding / achieve hydrodynamic equilibrium, and it would need at least 375km radius / 750km diameter (...or 750km radius?) for that to be assumed with any confidence, as there are some bodies composed of harder rock which approach this size without being sufficiently spherical to qualify. Thus the transitional zone would be about 200-400km radius (or more realistically 250-375km), i.e. 400-800km (or 500-750km) diameter. 209.93.141.17 (talk) 18:07, 24 September 2017 (UTC)[reply]

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Name, "known satellites"...

Are either of these correct? Starting at the end, if it's a binary system, Phorcys shouldn't be listed as a satellite - even the article text says that it was reclassified and renamed from originally being "Ceto I". As the smaller partner it should be the secondary to Ceto as the primary half of the pair.

Also, with Phorcys ~~seemingly~~ not having its own page (edit: I tried to navigate to it from a disambiguation page, and it redirected to Ceto anyway), should this entry be renamed 65489 Ceto-Phorcys? There are other binaries listed with names combining their original separate names with a hyphen in between, and the primary's minor planet number being used for both. It would also make links from other articles less ambiguous, such as the section of the main Centaur article that makes mention of binaries where it lists examples in the very untidy form "AAA and BBB and CCC and DDD", where "AAA and BBB" is one binary system, and "CCC and DDD" is another... but "AAA-BBB and CCC-DDD" would be much clearer and possibly more correct (...with "xxx AAA-BBB and yyy CCC-DDD" including their MP#'s as xxx and yyy even moreso).

It's a bit too uncertain for me to be sure about "being bold" and unilaterally changing it, and maybe ending up having to change a whole lot of others as well, but it seems worthy of consideration. 209.93.141.17 (talk) 18:15, 24 September 2017 (UTC)[reply]