As the title states, If earth were the size of a marble would it be smoother than a marble?

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    $\begingroup$ I'm voting to close this question as off-topic because it isn't about Astronomy. It stems from a humorous meme - may be acceptable on Skeptics if it had a notable claim. $\endgroup$ – Rory Alsop Aug 14 '15 at 10:57
  • $\begingroup$ darn it sorry, I didnt realise I was in the wrong fourm $\endgroup$ – AnonDCX Aug 14 '15 at 10:59
  • $\begingroup$ Skeptics does accept things like this but you need to demonstrate a notable claim (have a read of their scope page for guidance) $\endgroup$ – Rory Alsop Aug 14 '15 at 11:03
  • $\begingroup$ @RoryAlsop I wouldn't call this off-topic. I had a similar question in an undergraduate astronomy problem class. It's a useful question to make the huge scales of the solar system easier to picture. $\endgroup$ – FJC Aug 14 '15 at 15:38
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    $\begingroup$ Earth radius is 6600km. The Mount Everest is 8848m high. The Mariana Trench is 11km deep. They sum to $\approx$ 20km. Scaling it down by 100km -> 1cm, we get a ball with 1.2m diameter, with at most 2mm roughness. It would not be visible with free eye. $\endgroup$ – peterh - Reinstate Monica Aug 14 '19 at 0:37


This What-If page describes the case for 'smoother than a bowling ball"

These scans (along with various measurements of ball roughness1 tell us that a high-end bowling ball is quite smooth. If blown up to the scale of the Earth, the ridges and bumps[2] would be between 10 and 200 meters high, and the peaks would be between one and three kilometers apart:

By Earth standards, this is quite smooth; our highest mountains are 40 times higher.

And it is simple to continue the scaling process to show that the same holds true for marbles. (Although I have not found a good source of data from people who scan marbles...)

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    $\begingroup$ I've a collection of old marbles. Some of them from the 20's and 30's have big chips out of them from hard use on the playground. Scaling to earth size, the chips'd likely be 1500 km deep. Those marbles don't roll so well anymore. $\endgroup$ – Wayfaring Stranger Aug 15 '15 at 0:18
  • $\begingroup$ I'll bet used bowling balls are more chipped than factory new ones too and a bowling ball is kind of a specific item, where it's manufactured to be especially round so as to roll very straight, or, handle a spin just right. Still, it's as good an answer as any. The earth is quite round and it may well be rounder than a model. Jupiter by comparison is very smooth but visibly squashed and flattish, though it doesn't have any mountains. On the earth, the bulge is the most non round factor, not the mountains, but it's not visible to the naked eye and still quite round. $\endgroup$ – userLTK Aug 15 '15 at 7:33

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