Usually have a Green Asterisk for a colonizable planet. But if a planet is behind another, where they occupy the same space, only the asterix for the 'front' planet shows.

This means that if the 'front' planet is not colonizable then there is no asterisk to indicate that a planet behind it is. Has it always been this way?

Or is it because I used the map editor?

Is that what it means? I've always thought the asterisk meant that one or more of the planets in the stack was colonizable. Next time I play, I will have to carefully evaluate multis without an asterisk to see if I can find a planet under the top that I can use.

Please do, as I thought it worked how you describe ...that if any planet in the stack was colonizable then there would be an indication of that. But I have checked many examples on my current map ...and it is only showing the colonizability of the first planet in the stack.

Even if you have a red in front of a green ...then you will have a red asterisk. If you have a barren (uncolonizable) planet in front of a colonizable planet, then you will have no asterisk.

If my memory serves me right it's a planet with moons. It only shows the planet I think and not the moons.

Yes, that's the way it's supposed to work.

Only the "top" planet's asterisk will show. The others are presumed to be moons.

An easy way to check for missed colony moons is by using the planet list and filtering for only habitable worlds. Try sorting by size, too. If you've missed any habitable moons, you'll probably recognize them by system and name. That's much easier than checking every moon by hand.

I've never had problems remembering where breathable atmosphere planets and moons are. When I discover a new system that's one of the first things, if not the first one that I notice. It's such a important fact that the time it takes to look for it and the ease of remembering it is, well great I think.

I'm ashamed to say I've forgotten them before, but only in games with gigantic galaxy maps with a huge number of systems.