Question: Would a modern-day teen, trained in using the north star for directions when camping/hiking, notice a difference in how the “north star” (Polaris) works when transported suddenly to 1313 BCE?
Out of Egypt has children (up to age 14) from Arizona in 1995 time travel to Ancient Egypt (and later the Sinai Peninsula) around the time period 1313 BCE (no one knows the date of the Exodus, or the equivalent migration, but Jewish thought places it in this year). The modern-day kids don’t have to actually navigate, but some will try to figure it out anyway.
Basic constellations are common knowledge among American schoolchildren, especially ones like mine who do not live in an urban area. I expect most of them will know about the North Star (with at least a couple of them knowing how to find it).
Some of my characters are boy/girl scouts and, speaking from my own childhood training, would have learned how to find and use the North Star for directionality and travel. Others may have learned from family campouts, summer camp, or just from other children/adults.
They’ll know that the North Star always points north, no matter the time or configuration of the constellations. The other stars appear to circle around it.
Specifically, 12 year old Jon, an avid Boy Scout, would have camped in isolated areas and learned how to navigate both with a compass (which he has with him in Egypt) and with the North Star.
The North Star, however, has not always been the one we know, Polaris. Axial precession is a very slow process but one that will be relevant for the time period I’m looking at.
In astronomy, axial precession is a gravity-induced, slow, and continuous change in the orientation of an astronomical body’s rotational axis. In particular, it can refer to the gradual shift in the orientation of Earth’s axis of rotation in a cycle of approximately 25,772 years (2150 years per zodiacal sign). This is similar to the precession of a spinning-top, with the axis tracing out a pair of cones joined at their apices. The term “precession” typically refers only to this largest part of the motion; other changes in the alignment of Earth’s axis—nutation and polar motion—are much smaller in magnitude.
Axial precession. Wikipedia.
This means that even 3000 years is enough to change the orientation of north in relationship to the stars.
A consequence of the precession is a changing pole star. Currently Polaris is extremely well suited to mark the position of the north celestial pole, as Polaris is a moderately bright star with a visual magnitude of 2.1 (variable), and it is located about one degree from the pole, with no stars of similar brightness too close.
The previous pole star was Kochab (Beta Ursae Minoris, β UMi, β Ursae Minoris), the brightest star in the bowl of the “Little Dipper”, located 16 degrees from Polaris. It held that role from 1500 BC to AD 500. It was not quite as accurate in its day as Polaris is today. Today, Kochab and its neighbor Pherkad are referred to as the “Guardians of the Pole” (meaning Polaris).
Axial precession. Wikipedia.
This picture shows the Little Dipper constellation with the current North Star, Polaris, just past the end of the Little Dipper handle, and the former North Star, Kochab, in the top right corner of the dipper (when rotated to “hold water”).
The night sky is a huge big deal in low-artificial-light areas, so everyone will notice it and talk about it. It will become an even bigger deal when they leave Egypt and enter the Sinai Peninsula and people are trying to figure out where they’re going. So no way will my characters (ancient and modern) not talk about this.
Even with modern light pollution (which blankets most of the planet), the night sky taken very close to Barberry Lake is so bright as to be overwhelming.
To find Polaris (our current North Star), either find the Little Dipper and look for the star at the end of the handle or find the Big Dipper and (after orienting it so the dipper is upright), follow the line made by the right side of the dipper upward (which might actually be towards Earth) until you reach a bright star.
To find Kochab (the North Star of Ancient Egypt), orient the Little Dipper so it’s upright then look for the bright star at the upper right hand corner of the dipper.
Let’s take a look at what the sky looks like for my characters. Using the application Stellarium, I’ve set up the views. The graphics are a bit hard to see but they’ll enlarge if you open them up in a new window or tab. While we don’t know the exact location or date of the Hebrew slave settlement, I’ve given it my best guess.
Prescott, Arizona, April 28, 1995 8pm
Prescott is very close to my fictional town of Barberry Lake and the children depart for Ancient Egypt on April 29, 1995. If Jon (or other characters) look at the sky on the evening before they leave, this is what they’ll see.
Note how the Little Dipper spins around over the course of the night but the end of the handle, which is Polaris, is always practically on top of the North Celestial Pole (NCP).
Prescott, Arizona, April 29, 1995 Midnight
Faqus, Egypt, March 28, 1313 BCE 8pm
Faqus is in the East Delta region of Egypt, approximately where you might expect the Hebrew slaves to have lived. Even if it’s off by a bit, the sky wouldn’t be very different. I made a guess as to time of year by the Gregorian calendar (we know the Hebrew date). The year is traditional Jewish belief, but it could be way off.
Note how the Little Dipper still spins around just like it does today. But the center point is different. Polaris is nowhere near the North Celestial Pole. Actually, the pole is dark. But Kochab is the closest. It is not really a “North Star” but it’s in the right vicinity.
Jon or any other modern-day character who knew how to find Polaris would be very confused. Instead of a tiny little circle around the NCP, Polaris here is making a huge circle that takes up a big swath of sky. The circle Kochab makes is smaller but still prominent.
Faqus, Egypt, March 29, 1313 BCE Midnight
Here’s a video of the rotation (sped up considerably). It spins around completely in about 24 hours.
In Ancient Egypt and elsewhere, finding north (if you’re in the northern hemisphere) is important, but compasses weren’t invented yet. So even without Polaris to guide them, they had their ways.
From around 2500 BCE, as Thuban became less and less aligned with the north celestial pole, Kochab became one “pillar” of the circumpolar stars, first with Mizar, a star in the middle of the handle of the Big Dipper (Ursa Major), and later with Pherkad (in Ursa Minor). In fact, around the year 2467 BCE, the true north was best determined by drawing a plumb line between Mizar and Kochab, a fact with which the Ancient Egyptians were well acquainted, as they aligned the great Pyramid of Giza with it. This cycle of the succession of pole stars occurs due to the precession of the equinoxes. Kochab and Mizar were referred to by Ancient Egyptian astronomers as ‘The Indestructibles’ lighting the North. As precession continued, by the year 1100 BCE, Kochab was within roughly 7° of the north celestial pole, with old references over-emphasizing this near pass by referring to Beta Ursae Minoris as “Polaris”, relating it to the current pole star, Polaris, which is slightly brighter and will have a much closer alignment of less than 0.5° by 2100 CE.
Beta Ursae Minoris (aka Kochab). Wikipedia.
References
- How to calculate rate of axial precession? Worldbuilding on StackExchange, 2019.
- The North Star in the ancient world sky. Worldbuilding on StackExchange, 2019.
- Axial precession. Wikipedia.
- Beta Ursae Minoris (aka Kochab). Wikipedia.
- Pole star. Wikipedia.
- Mizar. Wikipedia.
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