Astrophysical dimensions are usually too much for me to visualize, without,
er, visuals, so after shooting my mouth off earlier about the planetoid being near in size to Pluto's Charon, I took the next self-edificational step and googled to find out how big is Charon (comparable to the '1,200 km' bit) and was amazed to discover it is
smaller than the Moon. (Yes, it sometimes take me a bit long to get around the block, but I get there...)
I guess even with its own
montes (and the 5.5 km Mons Huygens)
, it is still pretty easy to see the moon's horizon.
So, I'm still open to interpretations on the size of the eldritch planetoid (aka LV-426).