Some of the reasons are not very compelling. Some thoughts: 4. Other planets are spherical: This rests on the premise that earth is also a planet. This is also

Some of the reasons are not very compelling. Some thoughts: 4. Other planets are spherical: This rests on the premise that earth is also a planet. This is also the problem with no. 5. 8. Shadows of sticks: The earth could be flat and the sun could be small and close. 11. Gravity: This requires that the law of gravity can be derived independently from the fact that the earth is spherical. That's not easy.