The moon is 1/400th the size of the sun but also 1/400th the distance from Earth which results in the moon and the sun being the same size in the sky, a coincidence not shared by any other known planet-moon combination.

submitted by Orangutan from earthsky.org

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[–]RoxannaHardbutt 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (5 children)

..the Moon and the Sun being the same size in the sky, a coincidence not shared by any other known combination.

I disconcur .. the sharp eclipse shadows photographed on planet Jupiter by various spacecraft, indicate the eclipsing body and the Sun are the same relative size in the Jovian sky, just like the Sun and the Moon seen from Earth.

[–]Tom_BombadilBombadildo 2 insightful - 1 fun2 insightful - 0 fun3 insightful - 1 fun -  (4 children)

I disconcur .. the sharp eclipse shadows JPG photographed on planet Jupiter by various spacecraft, indicate the eclipsing body and the Sun are the same relative size in the Jovian sky, just like the Sun and the Moon seen from Earth.

The "sharpness" of the eclipse shadows has nothing to do with the angular diameter/area that a planet's moon(s) occupys in the sky from a given location

If the Earth's moon were closer in orbit, then it's angular diameter would increase. If it were farther, then the angular diameter would decrease.

The fact that the moon and the sun have equal angular distances is almost incredible. Literally.

The Earth's moon is quite large relative to the size of the Earth..

The Earth is much smaller than Jupiter.

[–]RoxannaHardbutt 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (3 children)

The well defined eclipse shadow seen on Jupiter does indeed prove the eclipsing body subtends the same angle in the sky as the Sun, a similar sharp shadow has been imaged on planet Uranus during an eclipse by its satellite Ariel proving both bodies have the same angular dimension, that eclipses on planet Mars never produce sharp shadows is because neither of its moons has sufficient angular width to cover the disc of the Sun, likewise if the eclipsing bodies on Jupiter and Uranus were smaller or larger their shadows would never be in focus. Edit.

[–]Tom_BombadilBombadildo 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (2 children)

Subtending is irrelevant as light from the sun at these distances can be considered parallel rays; for all practical purposes.

[–]RoxannaHardbutt 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (1 child)

You'll be on about the Flat Earth next ..

[–]Tom_BombadilBombadildo 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (0 children)

Accretion disk. Not Earth.