What do the gray/silver crown icons mean in Super Mario Galaxy 2?

In Super Mario Galaxy 2 for the Nintendo Wii, when choosing a galaxy to go to, some galaxies have a gray (or maybe silver is a better description) crown-like icon next to them. I can't tell if this is indicating that I have already received a silver crown, or if it's a grayed-out version of a colored crown (gold maybe?) which I have not yet received.

Does anyone know what I'm talking about and if so, what do these crown icons signify? I'll try to find a picture if nobody understands what I'm talking about...

Solution 1:

The silver crown means you have collected every star and the comet medal in a particular galaxy. After getting 120 stars, more things to collect unlock in each galaxy. When you collect all of those the silver crown becomes a gold crown.

To clarify, it has nothing to do with how many coins you get.

Solution 2:

The gray crown means you have gotten everything you can get (all stars and the comet coin) in a Galaxy prior to getting 120 stars. Later on, after you have gotten 120 stars, there are additional things to do in each Galaxy - completing all of those will get you a gold crown.

It's a quick indicator of whether you have completed a Galaxy. If you don't see a crown, you need to go back!