It might seem a bit far-fetched but yes, it’s true: if you could line up all of the other planets in our Solar System in a row edge-to-edge (or more geometrically accurately, limb-to-limb) and for good measure even include Pluto, the entire queue would easily fit within the space between Earth and the Moon.
(Not that this is something I advise doing, of course—the resulting tides would wreak havoc on the marinas and beachfront properties.)
So how can this work?
If you take the equatorial diameters of all the other planets—and include Pluto’s updated diameter of 2,375 km but not include the main rings of Saturn, which themselves (out to the F ring) span three quarters the distance to the Moon—and add them together, you get a sum of 390,316 kilometers (242,531 miles).
That’s 15,380 km (9,556 miles) less than the 405,696-km (252,088-mile) distance of our Moon when it’s at apogee, the furthest point* in its 27.3-day-long orbit around Earth.
That remaining gap is even big enough to fit an entire Earth into—with 2,624 km (1,630 miles) to spare! So you could accurately say ALL of the planets could fit between Earth and the Moon…including Pluto and Earth itself.
Now like I said, we’re not including the size of Saturn’s rings in this imaginary (and quite impossible) lineup. But even without those Saturn is a dramatically oblate planet. Because of its rapid rotation rate (once every 10.2 hours) and low density it’s much wider around its equator than it is around its poles—with a difference of 11,808 km (7,337 miles), in fact.
All of the planets are oblate to some degree, including Earth (with an equatorial-to-meridional diameter difference of about 43 km), but it’s most dramatic at Saturn.
So if we were to rotate Saturn 90 degrees on its side the other planets could snuggle in a little bit closer, bringing the entire queue length (without the extra Earth) to 378,508 km (235,194 miles). Then the planetary conga line would fit within the average distance to the Moon, which according to NASA is 384,400 km (238,855 miles)… and still have enough room left to fit the Solar System’s largest moon, Ganymede.
Again, this is not a scenario that could ever happen (and even if it could, it would be a really bad idea to make it so, for obvious reasons.) It’s just a numbers game. But it shows 1. how far the distance between Earth and the Moon is in relation to the size of planets, and 2. how much space there is across the expanse of the Solar System, when all of the major worlds in it could tuck inside the orbit of the Moon—in a row, no less.
And then when you manage to get a good grasp of all that in your mind, remember that the Sun in vastly larger than all those objects, it alone comprising about 99.8% of the mass of the Solar System. (And with all due respect it’s really just an average-sized, middle-aged, G-class star.)
“Space is big. You just won’t believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist’s, but that’s just peanuts to space.”
— Douglas Adams
*Note that all apogee/perigee distances are not the same; some are a little farther or closer than others just due to small variations in the lunar orbit over the course of a year and even from year to year. In fact the farthest apogee since 1750 will come on Feb. 3, 2125 when the Moon will be 406,720 km (252,724 miles) away! Read more on that here.