Post by Cryptoengineer Post by David Johnston Post by James Nicoll
Five Worldbuilding Errors That Should Be Banished from SF Forever
While it is true that stars move in all my time consuming science
fiction I can't think of a single story where I would stop and say
"Wait, that isn't possible /because stars move/". It's simply not an
issue. Certainly not a common error in worldbuilding.
If a time traveller moves more than 50,000 years or so, and mentions
recognizable constellations, its happening.
A different mechanism can throw off a time traveller's navigation even
faster: The precession of the equioxes. Polaris is currently within 1
degree of the pole (and getting closer), but in ~320 BC the navigator
Pytheas described the celestial pole as devoid of stars.
Smart time travellers use that to check their navigation.
Interstellar travellers take an interest in constellations.
When you said "recognisable" constellations, I thought you
meant "with visible differences, but identifiable".
More distant stars have less visible movement, but have
to be brighter to be seen.
My impression was that the common "example" of
Ursa Major, mentioned here as getting warped over
the next 50,000 years <https://spaceplace.nasa.gov/review/dr-marc-space/constellations.html>
(but without showing that), is unusually fast breaking up.
I say "common"; we may be remembering it from
the "Peanuts" cartoon?