The primary technique for estimating latitude is to measure (with your hand) the height of certain stars above the horizon when the star is crossing the meridian. As we approach Hawai'i we will be using the stars in the Southern
Cross to estimate our latitude. We need to measure how far above the horizon the stars are. Without a moon, it is difficult and often impossible to tell where the ocean stops and the sky begins; when the moon lights the horizon, we can see where it is and this allows us to make our measurements (one finger, two finger, three finger, etc.)