I believe that Mercury rotates still at about 1.5 times per revolution about the Sun. So, it does have a “day” and is, not yet, tidally locked to the Sun.
I think of it like a juggler tossing bowling pins around, but I could be wrong.
“I believe that Mercury rotates still at about 1.5 times per revolution about the Sun.”
I sit corrected. But in my defence, understanding what it does in rotation needs one smarter than me. You probably know more.
Here’s what I came up with and it would take a rocket scientist to understand:
“Mercury spins slowly on its axis and completes one rotation every 59 Earth days. But when Mercury is moving fastest in its elliptical orbit around the Sun (and it is closest to the Sun), each rotation is not accompanied by sunrise and sunset like it is on most other planets. The morning Sun appears to rise briefly, set, and rise again from some parts of the planet’s surface. The same thing happens in reverse at sunset for other parts of the surface. One Mercury solar day (one full day-night cycle) equals 176 Earth days – just over two years on Mercury.”
https://science.nasa.gov/mercury/facts/
If you can piece that one out, you’re pretty bright. Good on ya.
wy69