Ancient astronomers of course didn't have to deal with light pollution. And they were motivated. (As I recall, the priests at the temple in Jerusalem had to watch for the exact moment of sunset to start feasts like passover.)
Mercury's orbit isn't what one would expect based on Newtonian mechanics. That led to the theory that there was a planet called Vulcan even closer to the sun yet to be discovered, and there were hundreds of searchers and tens of "discoveries". After all, Uranus' eccentricities had led people to Neptune. But a guy named Einstein spoiled the fun in 1915 by predicting the anomaly with his general relativity theory--"close to the sun" means "higher curvature in space" and therefore "precession" in the orbit of Mercury.
Mercury rotates so it always shows the same face to the sun, which means that in craters near the poles in constant shadow water ice apparently exists (at least that's the conclusion from the probes that have gone there). Atmospheres matter when it comes to dispersing heat, and Mercury doesn't really have one (blown away long ago by the solar wind, I guess).
Supposedly, one of the joys of an Amtrak trip across the United States (there are also numerous sorrows with Amtrak, since it uses freight railroad tracks and loses its priority if it runs even a little late, leading to running a whole lot late) is sitting in an observation car at night and watching the stars out on the Plains. Where I live, there is way too much light pollution (and often a lot of clouds). I miss seeing the Milky Way which I used to see quite often years ago. Light pollution has skyrocketed here.