8  The search for Earth’s first cousins

Kepler’s small planets may be too distant for us to learn more about them, but the measurements have told us that we can expect several small planets to be in orbit around cool stars in much closer parts of the Galaxy. If they are close enough, then we may be able to measure their masses to determine whether or not they are rocky, and we might even be able to go further and find out what they are really like.