History  |  December 21, 2020
By Dr. Deborah Atwood, NMB Curator
Reading Time: 8 minutes

“Open your mind to the past. Art, history, philosophy. And all this may mean something.”

– Captain Jean Luc Picard

On December 21, 2020 Jupiter and Saturn will pass each other at their closest point in nearly 400 years. Known as a “Great Conjunction”, this phenomenon is even more notable this year as it will happen at night and be visible by the naked eye; the last time this event took place at night was almost 800 years ago. This rare phenomenon presents an opportunity to reflect and acknowledge the past while we look to the future.

First a little bit on astronomy. Astronomy, or the study of the celestial bodies –  the Sun, moon, planets and stars – is one of the oldest natural sciences in existence and an incredibly important part of human history. Humans have been fascinated with the heavens for millennia. Prehistoric cultures drew constellations on cave walls and built stone structures to mark the alignment of celestial bodies throughout the year.

Stonehenge is possibly one of the most famous stone structures built by ancient humans. If you would like to explore the skies above Stonehenge, check out English Heritage’s Stonehenge Skyscape: https://www.stonehengeskyscape.co.uk/

The Mayans, Chinese and Romans all used observational astronomy to track the movement of the sun, moon and stars and developed their own calendars based on those recordings. From Aristarchus, Eratosthenes, Hipparchus, Gan De, Ptolemy, Arybhata, Copernicus, Galileo, and Newton to Einstein, Hubble, Sagan, and Hawking, generations of astronomers and scientists have built upon the collective knowledge of their predecessors.

Based on this collective knowledge we now know that our solar system is made up of 8 planets, R.I.P. Pluto. In order from closest to the sun they are Mercury, Venus, Earth, Mars, Saturn, Jupiter, Uranus and Neptune. They vary in size and orbit the Sun at different speeds and a “Great Conjunction” between Jupiter and Saturn will occur when the two largest planets in our solar system pass by each other on their respective orbital tracks.

The data gathered by early astronomers was not only integral to our understanding of our location within the universe but also vital to the development of navigational aids that help ascertain positioning on land and at sea here on Earth. The work of early astronomers, mathematicians and marine scientists led to the improvement of navigational tools which provided the necessary skills for consistent and successful trans-Atlantic travel in the 15th and 16th centuries and the subsequent discovery of Bermuda.

Prior to the 13th century many Atlantic basin peoples were developing their own maritime technologies and travelling throughout the Atlantic but these crossings never developed into the maritime highways seen in other oceans and seas around the world. For example, Polynesians had long dominated the Pacific and Indian, Arctic and Mediterranean crossings had similarly been successfully traversed by ancient mariners.

However, political and economic developments in the 13th century saw European interest in the Atlantic increase and accelerated the development of an Atlantic maritime trade network. In his lecture The Early Atlantic Age (1250-1609): Why and how did we get here? Dr. Clarence Maxwell examines the political and economic events, which led to the construction of this Atlantic System and the discovery of Bermuda in 1505.

In 1226, the last time a “Great Conjunction” between Jupiter and Saturn was visible at night, Bermuda had not yet been discovered but the rest of the Atlantic World was about to hit a crucial moment, which would forever change the region and the rest of the world.

“[f]or the creation of the Atlantic world involved one of history’s great intercontinental migrations and the most massive cultural encounter and engagement that the world had seen up to that time.

– John Thornton

The largest obstacle to a trans-Atlantic crossing at the time was the Atlantic Ocean itself. The prevailing currents in the Atlantic, the Canary current and the Gulf Stream, essentially created a one way traffic system for sailing vessels. Vessels could follow the Canary current west to the Americas and the Gulf Stream back east to Europe, Asia and Africa but having little knowledge of this current system early Atlantic mariners could often find themselves at the mercy of the currents and end up thousands of miles away from home with no way of getting back and no points of resupply available.

“The Caribbean in particular had an impressive tradition of building and using watercraft, and even inter-island voyages might go astray, thus resulting in accidental trans-Atlantic voyages. As early as the first century BCE, the Roman writer Pliny noted the shipwreck of some people whom he described, with strange unintended irony, as “Indians” who were wrecked in Germany, from in his assessment, an ill-fated “trading voyage.”

– John Thornton

The accidental discovery of these “outbound” and “inbound” currents off the coast of the Azores by Christopher Columbus set off an age of discovery and expansion unlike anything seen in the region before. Even with this new knowledge, ocean navigation throughout this period was still highly inaccurate.

Sailors had only a rough idea of their location and even small errors could set a ship hundreds of miles off course. Because navigation was so critical to European territorial and economic expansion, huge efforts were put into developing reliable methods of finding the way across vast stretches of ocean. Developments in mathematics, navigation and astronomy helped propel marine sciences.

The nautical scientist at work. Without his discoveries, trans-oceanic navigation would not have been possible. Trustees of The British Museum.

To pinpoint the ship’s location on a chart, mariners needed to know their longitude (east-west position) and latitude (north-south position). Early mariners used celestial navigation, or astronavigation, which involved measuring and recording the position and movement of celestial bodies like the Sun, stars, moon or a planet, to estimate positioning. Navigational instruments have been found on shipwrecks in Bermuda including dividers, sandglasses, and navigational slates, which would have been used to record observations, ship’s speed and estimated positioning.

From the NMB Collections: Brass dividers, also known as chart compasses, were used by pilots to take measurements or transfer distances on navigational charts. Currently on display in the Museum’s Shipwreck Island exhibit, Queen’s Exhibition Hall.

From the NMB Collections: Sandglass, San Pedro, 1595. Usually there were two types of sandglasses aboard ship. A half-hour glass measured the length of each watch, and a smaller half-minute glass helped to determine the ship’s speed. Currently on display in the Museum’s Shipwreck Island exhibit, Queen’s Exhibition Hall.

The Renaissance brought about advances in nautical sciences and mapmaking, creating a boom in navigational schools, shipyards and production of navigation tools and equipment. Instruments, like the astrolabe, quadrant, cross-staff, and backstaff were used to measure the altitude of the sun and stars. Those measurements were then compared with almanacs and nautical tables to find the line of latitude.

However, accuracy varied and these instruments were difficult to keep steady at sea, increasing the likelihood of navigational errors. Visible navigational landmarks like Bermuda became key markers indicating that sailors were on the right course and were also vital way-stations for crews in need of supplies. Unfortunately, navigating around Bermuda could be a dangerous and costly endeavour.

Bermuda has hundreds of known shipwrecks, some of them 500 years old and these underwater time capsules attest to the Island’s importance within this Atlantic highway and the danger our encircling reef system presented for mariners. In 1505, Juan de Bermúdez uncovered one of the last New World islands to be discovered, Bermuda. With this discovery, Bermuda found itself on the Atlantic highway map and became an important navigational marker for ships bound for the Old World. However, faced with inaccurate charts, raging storms and no means of knowing their exact position, early European mariners were frequent victims of Bermuda’s reef system as they tried to return from the New World.

From the NMB Collection: Model of La Garza. Bermúdez was commanding La Garza when he spotted Bermuda in 1505. His ship was part of a fleet delivering some of the earliest enslaved Africans to work the copper mines in Hispaniola.

The last time Jupiter and Saturn made this passing, in 1623, Bermuda had been established as a colony under the Somers Island Company, Richard Norwood was compiling his survey of the islands, and the House of Assembly passed the first targeted legislation aimed at diminishing the economic and political power of black individuals in the Anglo-Atlantic World.

Four hundred years have passed and in that time, slavery was abolished, universal adult suffrage established, and Bermuda transitioned from a Company colony to a British Overseas Territory with her own constitution, laws and government. The acts of those who came before us led us to where we are today and left a legacy that we are still grappling with in many ways. When Jupiter and Saturn reset the clock on their orbital race to each other, let us look ahead and wonder what we’ll accomplish over the next four hundred years and what legacy we will leave for the generations that follow.

Manuscript map: ‘A Mapp or Description of Sommer Islands sometimes Called BERMUDAS Lying in the West Indies…’. A copy of Norwood’s 1663 survey made by Thomas Clarke, 1678. John Carter Brown Library.

As we approach the longest night of the year, on what has felt like the longest year ever, I encourage you to gaze upwards. See if you can spot Jupiter and Saturn on their orbital voyage and take a moment to reflect on how far we have come as a species and how far we still have left to travel together.

“Look again at that dot. That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every “superstar,” every “supreme leader,” every saint and sinner in the history of our species lived there–on a mote of dust suspended in a sunbeam.”

― Carl Sagan

If you want to check out this phenomenon yourself here’s how:

  • Find a spot with an unobstructed view of the sky, such as a park or beach.
  • 45 mins after sunset, approximately 6:00pm Bermuda time, look to the southwestern sky. Jupiter will look like a bright star and be easily visible. Saturn will be slightly fainter and will appear slightly above and to the left of Jupiter until December 21, when Jupiter will overtake it and they will reverse positions in the sky.
  • The planets can be seen with the unaided eye, but if you have binoculars or a small telescope, you may be able to see Jupiter’s four large moons – Io, Europa, Ganymede, and Callisto discovered by Galileo in 1610 a year after the Sea Venture landed at Bermuda – orbiting the giant planet.

Thornton, John. K. 2012. A Cultural History of the Atlantic World, 1250-1820. NewYork: Cambridge University Press.


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Planetary Facts:


The moon Io floats above the cloudtops of Jupiter in this image captured by
NASA’s Cassini spacecraft on the dawn of the new millennium, Jan. 1, 2001,
two days after Cassini’s closest approach to Jupiter. The image is deceiving:
There is room for two and a half Jupiters between Io and Jupiter’s clouds.
Io is the size of our Moon. Credit: NASA/JPL/University of Arizona

5th Planet from the Sun

Distance from the sun: 763,090,600km

Length of year: 11.86 Earth Years

Number of moons: 79

Largest planet in our solar system: 11 Earths could fit across Jupiter’s equator

Atmosphere: Hydrogen and Helium

Jupiter cannot support life as we know it. But some of Jupiter’s moons have oceans beneath their crusts that might support life.


The latest view of Saturn from NASA’s Hubble Space Telescope captures exquisite details of the ring system — which looks like a phonograph record with grooves that represent detailed structure within the rings — and atmospheric details that once could only be captured by spacecraft visiting the distant world. Hubble’s Wide Field Camera 3 observed Saturn on June 20, 2019, as the planet made its closest approach to Earth, at about 845 million miles away. NASA, ESA, A. Simon (GSFC), M.H. Wong (University of California, Berkeley) and the OPAL Team.

6th planet from the sun

Distance from the sun: 1,494,348,700km

Length of year: 29.47 Earth Years

Number of moons: 53 known moons, with 29 awaiting confirmation of their discovery – total of 82 moons.

Saturn is surrounded by thousands of complicated ringlets, made up of chunks of ice and rock.

Atmosphere: Hydrogen and Helium

Similar to Jupiter, Saturn cannot support life but some of its moons may be able to.

Reading Time: 8 minutes

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