Could all the other planets fit between Earth and the Moon?

The answer depends on where the Moon is.

Answer: sometimes. At the Moon’s average distance, the seven planets are slightly too wide for the clear gap. At its farthest distance, they fit. The familiar “fact” changes with the condition being measured.

How many “facts” depend on a condition we rarely mention?

Why doesn’t 384,400 km mean 384,400 km of empty space?

Earth–Moon distance is measured from the center of Earth to the center of the Moon. To find the empty space between their surfaces, subtract Earth’s radius and the Moon’s radius.

Average distance

384,400 − 6,371 − 1,737 = 376,292 km

That is the clear gap between Earth and the Moon.

380,010 − 376,292 = 3,718 km too wide

Farthest distance

405,500 − 6,371 − 1,737 = 397,392 km

That is the clear gap at the farthest distance used here.

397,392 − 380,010 = 17,382 km to spare

The seven other planets have a combined diameter of about 380,010 km.

Sources: NASA planetary fact sheets / Solar System Exploration for planetary diameters and Moon dimensions; NASA lunar reference values for Earth–Moon distance. This exhibit uses 363,300 km (closest), 384,400 km (average), and 405,500 km (farthest) as center-to-center distances and shows all diameters and distances on one scale.