How similar or different can an exoplanet be, that supports a convergent evolved ''human'' species?

The idea is that a species very similar, but not related to humans have evolved on a different planet and are living in a medieval society. Humans from Earth must be able to live on this planet without spacesuits but not necessarily pleasantly.

The planet must have the following traits to support this scenario:

1. One moon to keep the planet from spinning to fast. (multiple moons would likely collapse into each other or swing the poles too much)
2. Gravitational pull not stronger than 2~3 times that of Earth.
3. Terrestrial body with the right elements for the creation of life.
4. Atmosphere that is breathable and keeps water liquid.
5. Be within the habitable zone of a star.
6. Receive enough light for photosynthesis.
7. Have a magnetic field that protects from radiation.
8. A climate that supports medieval civilization.

I was thinking about having the planet a little further away from a bigger star or a little closer to a weaker star than Earth is to the sun so the photosynthesis would take on a different wavelength of color and the sun would look different changing the landscape. I also figured gravity and thus planet size could differentiate this place from Earth but I am not sure how this impacts on the other requirements.

posted almost 8 years ago

Geotheo‭

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