Help with a planet that resembles Mercury: double sunset/sunrise etc

Question

I'm new. I'm here because I need help for the geography of a fantasy planet I'm building. I don't want to be scientific, but I also want that my planet is credible. I imagined a planet that has maybe 7 earth days light and 6 earth days night, that has some Mercury's features, such as the orbit 3:2 and the movement of the sun (double sunset, double sunrise, the sun that becomes bigger at some point etc...)

Now my question is: Where should I place the cities in order to see the sun doing this stuffs?

For the story, one city should see the sun that stops above and becomes bigger and hotter. In this case the sun should also go backward when it's noon, right? If the sun goes backward when it's noon, this means that this city will never see a double sunset/sunrise, right?

Another city should see just a double sunrise/ sunset

Another city should see both.

I just need help to orient myself in this new world, so just explain things like "the city with double sunset should be placed near the North Pole while the city that have double sunset + double sunrise should be placed more South-East and the city that sees the sun bigger at noon should be place even more South, maybe near the equator line or just in the Southern Hemisphere"

I basically have to draw a map, but I don't know where to place the cities and at what distance to each other in order to see the double sunset/sunrise etc....I suppose that the view of the sun is different according to the longitude and latitude.

English is not my native language, sorry for my mistakes. Thanks.

Answer 1

The sun's apparent loop at perihelion is overhead at one of two points on the equator called the hot poles. The two hot poles are antipodal to each other, and the perihelion sun shines on them alternately.

At right angles to the line of hot poles is the line of warm poles, also on the equator, where the aphelion sun is overhead, likewise alternating. As seen at a warm pole, the crossing of the little loop is on the horizon; hence a double sunrise and double sunset.

As you suspected, you cannot see both phenomena – a double sunrise and an overhead loop – from the same place on Mercury. But your Mercury-like planet, though it must rotate slowly and have high orbital eccentricity, need not be in 3:2 resonance; if it has some other ratio, or indeed no resonance, the loop could happen at different places in the sky.

(I don't know what other resonances are plausible for a Mercury-like planet; I asked a related question years ago on astronomy.se and got nothing.)