Which is really hard to imagine, because we're not used to dealing with such huge numbers on an everyday basis.
So here's another picture to put it in perspective.
Every single planet could fit between Earth and the moon.
Here's the maths:
Earth-moon distance (384,440km) – [diameter of Mercury (4879km) + diameter of Venus (12,104km) + diameter of Mars (6771km) + diameter of Jupiter (138,350km) + diameter of Saturn (114,630km) + diameter of Uranus (50,532km) + diameter of Neptune (49,105km)] = 8069km.
Check with Wolfram Alpha if you don't trust us (they work it out as 8031km). The calculation uses the average distance between the Earth and moon, and the average diameters of each of the planets.
The calculation doesn't include Pluto, because Pluto is not a planet.
But its average diameter is only 2302km (1430 miles) anyway, so it would easily fit in too. (It's actually smaller than the moon.)
Some planets spin really fast so they bulge out around their middle.
This means their diameter through their equator is different to that from the north to south pole. If you start using all of the planets' largest diameters, they'd be too wide to fit between Earth and the moon.
But as long as you arranged the planets pole to pole you'd be fine. In fact, there'd be even more room than the picture above shows.