> How many exoplanets have been found, and how many of those are Earth-size planets with a large moon in the habitable zone of a sun-like star? I think this is

> How many exoplanets have been found, and how many of those are Earth-size planets with a large moon in the habitable zone of a sun-like star? I think this is down to how we look at the moment. One of the main ways we find exoplanets is to notice the star dimming with a regular frequency. This gets harder as the orbital time increases, as you need multiple observations of the planet transiting the star to conclude that it's a planet. This means that the vast majority of the exoplanets we know about have relatively short orbital periods, and the characteristics that go with that (e.g. they're close to their stars, therefore less likely to have moons, and if we consider them to be in the 'habitable zone', then their stars are relatively dim). Actually, the fact that we've found so many exoplanets that fit in the relatively limited criteria that we can detect, suggests to me that there are probably a lot of exoplanets of all kinds, that we're just not as good at detecting yet.