Sailing the Atlantic guided by the stars up to 3000 years before Columbus

Dr. Henk van Oosten, Rotterdam, the Netherlands (2022)

There have been some suggestions that ancient seamen were crossing the Atlantic Ocean from Europe/Africa to America and back thousands of years before Columbus. The Phoenicians, for example, might have crossed the ocean in the period between 1200 and 200 BC when they were the masters of the sea. In our own time, some sailors have managed to cross the ocean using replicas of ancient ships. But nobody has ever really explained how ancient sailors navigated this immense ocean, without any (known) instruments and lacking any landmarks for many weeks at a time.

Homer’s Iliad and Odyssey (8th century BC) are the earliest texts describing navigation by the stars. Possibly, this knowledge of celestial navigation was passed down through the oral tradition via stories told by seamen long before Homer’s time.

In the Iliad, Achilles’ shield was decorated with the sun, the moon, and four constellations: the Bear, Orion, the Hyades and the Pleiades, and Okeanos around the rim of the circular shield. Some constellations are mentioned in other parts of the text.

In the Odyssey, the goddess Calypso gave Odysseus instructions for his sailing voyage to the next destination. She used the constellations mentioned in the Iliad but omitted the Hyades and included Boötes. She also added that Odysseus should keep the Bear on his left, which implied sailing east to the home port.

Both the Iliad and the Odyssey mention that that “the Bear never takes a bath in Okeanos”, meaning that it never goes below the horizon.

In this paper I will present a method of sailing the Atlantic Ocean based on the knowledge of navigating with constellations mentioned in Homer’s poems. To study the stars, I have used the astronomical computer program SkyMap Lite 2005, which goes back as far as 4800 BC.

1. The Atlantic Ocean is Okeanos

Okeanos is most likely the Atlantic Ocean, an immense rough sea without any landmarks. It surrounds the known ancient world. There are tides here as well as a circular current: the Gulf Stream.

Okeanos is probably not the Aegean or the Mediterranean Sea. This is because both are seas within the known ancient world and with many landmarks close at hand. Moreover, neither has a tide (ebb and flow) nor a circular current.

2. Sailing the Atlantic Ocean in antiquity

In order to sail the ocean without instruments, a combination of several factors is necessary:

· The use of the Gulf Stream and the dominating wind direction

o The circular Gulf Stream moves south from Spain to Cape Verde (along the African coast) and west to the Caribbean (now about latitude 16.00 N). It then moves north-west to the Bahamas and Florida and north to Norfolk (along the American coast). Then it turns east to the Azores and to the home port Spain (36.00 N).

• Some islands along coasts have volcanoes which act as impressive landmarks.

• When sailors start from the Canary Islands (28.00 N) they first sail south-west using the existing current of the main Gulf Stream to avoid the windless area of the doldrums. The turn west to the Caribbean depends on the star configuration.

o The main winds blow from the north-west up to the Bahamas and mainly from the west or the north-west in the northern ocean

· The correct choice of season.

o To avoid extreme weather, you should set sail between the end of December and the end of February if heading west and between early June and early August if heading east.

o In each season of the year the position of the sun and the constellations is different.

· The position at night of the specific constellations mentioned in Homer’s poems.

o A crucial insight comes from Polynesian sailing techniques on the Pacific:

An imaginary perpendicular line drawn between a setting or rising star on the horizon and the star immediately above it indicates the direction to sail.

o The number of days between two full moons might be used to determine the duration of the voyage.

· The effect of the precession, the slow wobbling of the earth.

o Alterations have to be made over the centuries to the arrangement of the stars used for navigation.

o Several bright stars of the constellation Orion (Betelgeuse, Saiph, Alnilam and Bellatrix) are crucial when they are setting in the west and when they are rising in the east. Between 1500 BC and 2020 AD the perpendicular lines on the horizon shift gradually to other bright stars of Orion.

2.1. Sailing the Atlantic Ocean west from Cape Verde to the Caribbean guided by stars (figure 1).

a. 1400 BC: 3000 years before Columbus; 700 years before Homer

To the west: a line of the setting Betelgeuse and Procyon (Canis Minor) is perpendicular.

b. 900 BC: 2500 years before Columbus.

To the west: the line between the setting Betelgeuse and Procyon is no longer perpendicular as it was in 1400 BC but is leaning slightly to the left. A new perpendicular line between the setting Bellatrix and Procyon has developed.

c. 400 BC: 2000 years before Columbus

To the west: the line between the setting Bellatrix and Procyon is almost perpendicular, but leans slightly to the left.

d. 1492 AD: the year of Columbus

To the west: the line between the setting Alnilam and Procyon is perpendicular

e. 2020 AD: 500 years after Columbus; 2700 years after Homer

To the west: the line between the setting Alnilam and Procyon is almost perpendicular, leaning slightly to the left.

2.2. Sailing the Atlantic Ocean east from America to the Azores and Spain guided by stars (figure 2).

f. 1400 BC: 3000 years before Columbus; 700 years before Homer

To the east: a perpendicular line between the rising Saiph and Aldebaran (Hyades).

g. 900 BC: 2500 years before Columbus

To the east: a perpendicular line between the rising Alnilam and Aldebaran.

h. 400 BC: 2000 years before Columbus

To the east: a perpendicular line between the rising Alnilam and Aldebaran.

i. 1492 AD: the year of Columbus

To the east: the line between the rising Bellatrix and Aldebaran is perpendicular

j. 2020 AD: 500 years after Columbus; 2800 years after Homer

To the east: the line between the rising Bellatrix and Aldebaran is almost perpendicular, leaning slightly to the left.

3. The heliacal rise of stars and constellations

There may be additional information for sailors when stars or constellations rise shortly before sunrise. In several cultures this event may be interpreted as a sign marking the timing of agricultural practices or the way temples are built. Is this the case with the constellations in Homer’s poems? What could be the significance at sea?

The heliacal rise of some stars or constellations gives additional information about the continuation of the voyage:

1. End of April: the heliacal rise of the Pleiades. Message: leave the Caribbean and try to reach the Bahamas by early June;

2. First half of June: the heliacal rise of Orion. Message: if crossing the ocean to Spain you must leave the Bahamas within the first half of June.

3. Second half of July: the heliacal rise of Sirius (Canis Major). Message: Find a harbour as northern storms are getting wilder.

4. Early September: the heliacal rise of Spica (Virgo). Message: go home before the winter storms.

4. Are other constellations (zodiac, polar star) used for orientation?

There is no information in Homer’s Iliad and Odyssey about these constellations. Therefore, I have not used them. The setting of Aries and the Hyades may have played a role in the westward journey. The Phoenicians have discovered the polar star (Ursa Phoenicia).

5. Why is Homer’s Odyssey not on the Mediterranean Sea?

The Mediterranean is rather narrow. Star navigation is difficult to the west and the east because of the danger posed by the many islands and coastlines nearby.

The detour Calypso suggested to Odysseus is possible on the Atlantic but not on the Mediterranean. The fact that Boötes (setting in the north-west) and the Pleiades (rising in the east) are mentioned together implies a south-east heading on the Atlantic Ocean to the Canary Islands. On the Mediterranean this detour would end in the desert!

6. Conclusion

The circular Okeanos and the constellations in Homer’s poems guide sailors to the west and back to the home port in the east. The circular Okeanos is most likely the circular Gulf Stream of the Atlantic Ocean. When following the Gulf Stream, the constellations help sailors keep on track when heading west to America or east to their home port in Europe.

More information and references: Achilles’ Shield Decoded. The key to Homer’s Odyssey and the Trojan War (lulu.com)

figure 1: Sailing the Atlantic Ocean from Spain to America guided by the stars

figure 2: Sailing the Atlantic Ocean from America to Spain guided by the stars