If Sweden was to magically float away, at what altitude would it be visible from the southern hemisphere?

If a chunk of land mass the size and position of Sweden took off and floated away in a straight line, exiting the atmosphere and orbiting earth, at what distance would it be visible from, let's say, South Africa?

Alternatively, what size would our planet have to be to allow for such a floating land mass to be visible from the proportionate equivalent of South Africa, while still within the bounds of the planet's (unchanged) atmosphere?

Edit: Thanks for all your detailed and interesting answers! Didn't expect my silly question to blow up like that, tbh.

I was quite tired when I first posted and realize that I haven't specified some things properly.

Originally, I had intended for floating Sweden to remain geostationary, orbiting with the planet rather than around it (because magic). I thought perhaps the atmosphere's refractivity (which only @Chronocidal mentioned as far as I've seen) might allow for a high enough Sweden to be visible on the horizon, if the observer was positioned at the northernmost point of South Africa, with no obstacles in his line of vision, at maybe 1500 meters above sea level.

But in light of the response here, I decided to just have my floating island properly orbit the planet somewhere within the thermosphere instead.

posted over 5 years ago

Pangolin‭

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