I can't understand why anyone would be confused by this. We learn about 24h time format in primary school! It's also extremely easy to just subtract by 12.
The bigger aplanet, the further away its surface from its center of mass, which decreases gravity. A planet's surface gravity is mostly affected by its mass and density. This is why Saturn, despite being much bigger than Earth, still have roughly the same surface garvity.
How do they do it? Asking for a ~~friend~~ dolphin