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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 1350 BCE?

My novel has children (up to age 14) from the Southwestern United States in 1995 time travel to Ancient Egypt (and later the Sinai Peninsula) around the time period 1350 BCE. They are being looked after by local people and they join them on the Exodus (yes, that one) out of Egypt. 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.

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.

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). (ref)

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 left bottom corner of the dipper (when rotated to "hold water"). An enlargement of the graphic is here.

enter image description here

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.

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  • $\begingroup$ I clarified the relationship between the kids and the locals, per mentions of that in questions so far. $\endgroup$ – Cyn says make Monica whole Aug 1 '19 at 18:27
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The short answer is: Yes, they absolutely would notice a difference. As you noted, Kochab was the closest star to the North Celestial Pole during the time you mentioned, but even so, it wasn't near enough to be an actual pole star. In fact, Kochab never gets closer than 7 degrees to the NCP, which is about 14 full moon widths.

The simulated skies would appear as the left side of the image below:

Sky comparison in 1350 BC (left) vs 2019 (right)

As you can see, there is no pole star at the time you mention, and even though Kochab is close, it's still much farther than Polaris is today (Polaris is actually the second-best pole star after Alpha Draconis over the Earth's 26,000 year cycle, we're all just lucky to be born today).

Anyone staying put and watching Polaris during the time would find that it moves in a circle around the NCP, but that the pole itself would be dark.

Naively attempting to use Polaris or Kochab as a navigational aid would cause them to travel in a Northwesterly arc, rather than due North, as the stars moved around the pole, but so long as the person knew that Polaris and Kochab were not directly on the NCP, they could still use them to navigate.

So yes, they would notice a difference if they were paying attention, but if they just found themselves there at night and didn't know they had been transported 3000 years in the past, or didn't think to account for stellar drift, they could get lost simply trying to use what they know about stellar navigation today.

Another problem they might find is that the sheer number of stars away from light pollution makes it a little difficult to find your bearings. This is something I noticed myself when I went from a highly light polluted sky to a sky completely devoid of light pollution. Despite being an astrophotographer, I had a lot of difficulty picking out the skymarks and constellations I normally would have no problem finding in the suburbs. Unless you've been under a completely dark sky a few times, it's very easy to get overwhelmed.

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    $\begingroup$ Thanks! What did you use for the simulation? The links I've seen don't allow projections far back enough. They do know they've time traveled and about how far, and are being taken care of by locals (I edited my question to include that). And I agree with you about how overwhelming the true night sky is, and I've never been to a 100% dark location (closest was Arches National Park in Utah USA). These kids are from a small town in rural mountains and most would have gone camping, so they'd have seen a decent night sky. $\endgroup$ – Cyn says make Monica whole Aug 1 '19 at 18:30
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    $\begingroup$ I used Stellarium. It's a free and open source piece of software for viewing the night sky. $\endgroup$ – stix Aug 1 '19 at 19:04
  • $\begingroup$ Hmmm...that was one of the ones recommended to me but I didn't figure it out yet. I tried another one and it didn't go back nearly far enough. $\endgroup$ – Cyn says make Monica whole Aug 1 '19 at 19:10
  • $\begingroup$ For Stellarium you have to use negative years (i.e. -1350) if you want to put something in B.C. $\endgroup$ – stix Aug 1 '19 at 19:17
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    $\begingroup$ Wow there is a learning curve on that software, but I got it (you have to put in a very low number then use the arrow key until it's negative then change the number). Bookmarked the right date, year, and location. And how cool is that to see what my characters would see at night? Including sped up and around a north marker. And whoa, Polaris is totally off. Kochab isn't terrible but it's not like Polaris in modern times. It's far off enough that, with the compass one of them brought, it should be obvious the stars have moved. $\endgroup$ – Cyn says make Monica whole Aug 1 '19 at 21:36
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Yes, they will.

If you look at movement of the stars at night, it looks like all stars circle around Polaris. That's because it is very close to the axis of Earth's rotation.

The same wiki from which you took the image in the question also says:

In 3000 BC, the faint star Thuban in the constellation Draco was the North Star, aligning within 0.1° distance from the celestial pole, the closest of any of the visible pole stars. (...)

During the 1st millennium BC, Beta Ursae Minoris ("Kochab") was the bright star closest to the celestial pole, but it was never close enough to be taken as marking the pole, and the Greek navigator Pytheas in ca. 320 BC described the celestial pole as devoid of stars. In the Roman era, the celestial pole was about equally distant between Polaris and Kochab.

Then we go to Beta Ursar Minoris's wiki, and it says:

From around 2500 BCE, as Thuban became less and less aligned with the celestial north, 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, circa the year 2467 BCE, the true north was best observed 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 continues, by the year 1100 BCE Kochab is within roughly 7° [SIC] of the northern celestial pole, with old references over emphasizing this near pass by mentioning 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 AD.

This change in the identity of the pole stars is a result of Earth's precessional motion. After 2000 BCE, Kochab and a new star, its neighbor Pherkad, were closer to the pole and together served as twin pole stars, circling the North Pole, from around 1700 BCE until just after 300 AD. Neither star was as proximitous to the celestial north pole as Polaris is now. Today, they are sometimes referred to as the "Guardians of the Pole."

So from these, we can infer that:

  1. In the era your protagonists are transported to, stars would seem to circle around an area close to Beta Ursae Minoris, not Polaris;

  2. If your teen protagonists are smart enough to know about Polaris, they will know that the true North is more related to a seemingly empty patch in the sky than Polaris.

  3. If they know about precession, they will understand why this is so, and it won't bother them much.

It will still be easy to find the North through the stars. Here in the south the star closest to Earth's axis is very far from it, and yet we manage :)

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    $\begingroup$ On the Earth's 26,000 year cycle, Beta Ursae Minoris doesn't come within 7 degrees of the NCP, compared to Polaris's 0.5 degrees. 7 degrees is about 14 full moon widths away, so the stars would never seem to circle around Beta Ursae Minoris. $\endgroup$ – stix Aug 1 '19 at 16:48
  • $\begingroup$ @stix probably a typo in the wiki? Maybe they meant 0.7º. I added a [SIC] to it. $\endgroup$ – Renan Aug 1 '19 at 16:57
  • $\begingroup$ I'd say 7 degrees is probably correct. The Wikipedia page on pole stars describes it as a "near-north star" not an actual north star. Easy way to find out would be to load up Stellarium and set the date for 3000 years ago tho... Edit: Just checked in Stellarium. Yes, Kochab is very far from the NCP and doesn't stand still at all. $\endgroup$ – stix Aug 1 '19 at 17:09

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