Sorry for the pedantry, but Earth is not a "relatively small" planet. It's actually quite large for a rocky planet. Out of all the rocky planets and moons in our own system, Earth is by far the largest (except for Venus, which is about 90% the size). From what we're seeing with exoplanet research, it looks like Earth is still pretty large, though it's hard to tell since we have a hard time detecting smaller planets, and the "super-Earths" are more easily visible to us.

Of courses, compared to gas giants, Earth is small, but that's like comparing apples and whales.