The shortest distance across the strait, at approximately 20 miles (32 kilometres), is from the South Foreland, northeast of Dover in the English county of Kent, to Cap Gris Nez, a cape near to Calais in the French dรฉpartement of Pas-de-Calais.
From Quora:
On a clear day, you can indeed see from the TOP of the famous โwhite cliffsโ of Dover all the way across to France. I grew up living in a nearby village and my parents and I went to the tops of the cliffs most weekends during the summer.
The distance from the highest cliffs in the area to โCap Gris Nezโ (the closest point in France) is 20.7 miles.
The cliffs are 350 feet tall โ and this Distance to the Horizon Calculator says that (assuming the Earth is Round) from 350 feet, you can see 22.9 miles โ so this observation certainly doesnโt disprove that the earth is round.
HOWEVER (and Iโve actually done this a gazillion times) if you go down to the beach at the bottom of the cliff โ you can no longer see France. Same day, same visibility, same everything.
If I plug the number: 5.5 feet (the height of my eyes from the ground) into the horizon calculator, it predicts that Iโll be able to see 2.9 miles from the beach and therefore Iโd have zero chance of seeing any part of France from there.
If the Earth was flat โ Iโd be able to see France from the bottom of the cliff as well as from the top.
Hence, not only does this fail to prove that the Earth is flat โ it actually conclusively proves that itโs NOT flat!
Interestingly, the tops of the famous white cliffs are the only place in the whole of the UK from which you can see Franceโฆbecause none of the surrounding cliffs are high enough and the English channel is at itโs narrowest at that point
