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minor planet with a large moon, or a binary minor planet?
As per a similar question on Ceto's talk page - if it's a binary system, then surely Echidna isn't actually a moon but instead the smaller of a twinned pair of minor planets? Particularly given that the latter is more than half the size of the former, and they orbit so close together (presumably around a barycentre external to both). Also, should the page title remain as-is, or become 42355 Typhon-Echidna as seen with some other binaries? Unless of course they've been renamed Typhon A and Typhon B but that information hasn't made it to the article yet...
Additional - what is the correct (or at least most up to date estimate for the) size of Echidna? The main text says approx 89km diameter, but the sizebar says approx 134km diameter... so we can't even assume a mistaken reading of radius as diameter or similar. One of them must be wrong (even if the other isn't precisely correct but merely within a different estimated range), so which is it? 18.104.22.168 (talk) 18:23, 24 September 2017 (UTC)
134 km refers to Typhon. Ruslik_Zero 20:13, 24 September 2017 (UTC)