The sailors of antiquity studied the night sky. Reading the sky map, they could sail away from sight of the shore, knowing that steering by certain reliable stars would bring them home. This crude, practical application of Astronomy allowed the adventurous to sail into the unknown with a reasonable chance of finding their way. Wind-powered ships risked longer voyages, tempted by the knowledge, trade, and new settlements offered by distant lands. The maps of the known world expanded as the blanks were filled in by the reports of the sailors who had mastered Navigation.