Bodie Island Lighthouse, Nags Head, North Carolina

© Michael Ver Sprill/Getty Image

One on land, a million in space. National Lighthouse Day

A beacon, a warning and a symbol of hope and home, lighthouses have existed for thousands of years. The earliest known lighthouse, the Pharos of Alexandria, stood an estimated 100 metres tall, but in essence was a grand, elevated fire platform. Illumination technology advanced over the centuries, culminating in today's electric lighthouses that can be seen from over 32 kilometres away at sea level. Bodie Island Lighthouse, built in 1872 and seen in today's image, overlooks a section of ocean known historically as the Graveyard of the Atlantic. Since then, it's been doing its best to outshine the stars above it as it guides sailors home to safe harbour.