6.4 One region on the Moon is covered with craters<span>, </span>while another is a smooth volcanic<span> plane. Which is </span>older<span>? How much </span>older? How do we know<span>? The </span>crater-covered<span> surface is close </span>to<span> the same age as the</span>Moon<span> is - about 4 billion years. ... enshrouded in clouds, how </span>do we know<span> as much as we </span>do<span> about its surface?</span>
