I’m sure many of us will recall the time when we looked up into the night sky in all its majesty, saw the stars in their glory, and thought to ourselves, “THAT’S supposed to be a LION? What were those ancient astronomers smoking?”
“Am I the King of Beasts or a coat hanger?”
About the only constellation that actually looks like its name is the Big Dipper, and that’s not even recognized by the International Astronomical Union. It’s officially part of a bear.
“More poorly defined than the av-e-rage bear, eh, Ursa Minor?”
Although most of them have Latin names, the constellations we recognize today largely come from the Greeks, and tend to be associated with their mythology. Leo is the lion Hercules killed and then wore its skin everywhere he went. Ursa Major is one of the many women with whom Zeus was having an affair, so Hera turned her into a bear. Was the mythology developed to fit the stars, however, or vice versa? We can’t always tell, but it is known that many of the constellations actually date back to the Sumerians and Babylonians. If Wikipedia is correct that these names weren’t adapted by the Greeks until the fourth century BC, when much of the mythology would have already been written, then they likely just associated the figures from the Middle East with ones in their own stories. It’s not always clear exactly what constellation ties in with what myth, either.
Canis Major, for instance, has been identified as Orion‘s hunting dog, Europa’s guard dog who couldn’t protect her from Zeus, a gift from Zeus TO Europa, and Geryon’s two-headed dog. It’s also mentioned on Wikipedia that Sirius, the brightest star in Ursa Major that’s often known as the Dog Star, affected the behavior of dogs, and that the Dog Days when Sirius is in the sky might have meant that only a dog would go outside in that kind of heat. The mythical explanation I’ve heard for Cancer is that it was a crab that attacked Herakles while he was fighting the Hydra, which really adds nothing to the story and seems to be tacked on. I don’t know when the crab first appeared in this tale, but I can’t help imagining someone saying, “Hey, there’s no story we can associated with this crab constellation!”, with the reply, “Eh, just tack it on to Herakles somehow. He’s fought every other kind of animal at some point.”
The fact that Herakles had twelve labors and there are twelve constellations in the zodiac (which, in turn, is probably because there are twelve months in a year) has inevitably led to attempts to tie the two together, but people who attempt this really have to stretch on occasion. Speaking of stretching, Ursa Major and Minor are sometimes said to have longer tails than most bears because Zeus stretched them out when pulling them into the sky. I’ve seen it suggested that this was actually due to the Greeks seeing the bear as reversed from how earlier cultures did, and that the Big Dipper part was originally the HEAD of Ursa Major.
Of course, the constellations only have any meaning when seen from Earth, or at least near Earth. The stars that we see as grouped together are often actually many light-years apart. This is why it’s kind of weird when stories that involve interstellar travel still have the characters using our own designations for stars, although I suppose that’s really for our benefit. The green-skinned Orions in Star Trek, for instance, probably don’t call THEMSELVES by the name of a constellation visible from Earth. (According to Memory Alpha, their home star is Pi 3 Orionis, a designation that only makes sense when seen from an Earthly perspective.)
And it’s not like we don’t have plenty of precedents for foreigners using a different name for a place than its actual inhabitants. For instance, the people who call themselves Deutsch are known as Germans in English, while Spanish speakers call the country Allemagne. Wikipedia’s page on Sirius in fiction lists several works in which its planets are inhabited by dog-like beings, including Lucian of Samosata’s True History and a sequel to 101 Dalmatians (the book, not the movie) that I’d never heard of before. There was also “a party of Young Conservatives from Sirius B,” described as “smartly dressed young dogs,” eating at Milliways in Douglas Adams’ The Restaurant at the End of the Universe. As far as I know, however, these were all intended to be humorous, and this association hasn’t been made in more serious (pun intended) science fiction. But then, how many works of fiction are there that make Martians belligerent, as per their planet being named after a war god? Our names for these celestial places tend to stick in the public consciousness.