Hi all,

Another writer here doing research for an ancient historical novel.  The Pleiades cluster is central to my story.  I need my main character to be able to see the cluster very clearly above the horizon at nighttime (around 10pm).  The setting is an island near the Canaries.  The date is about 9,000 B.C..  My question is:  during what time of year would my main character be able to see the Pleiades around 10pm?  I figured out from my research so far that if the story was set present day, September or October would work best.  I'm assuming that things would have looked different 11,000 years ago.

Big thanks for any assistance you can give me!

Andy 

 According to my Starry Night program (depending on it's accuracy), the Pleiades would have been visible from January 1, 900 BC to March 3, 900 BC. Then again, September 9th  thru December 31, 900BC. 

Thanks Kevin.  I'm going back even further in my story - 9,000 B.C.  Is it possible for you to make that calculation?

AyJay:

Thanks Kevin.  I'm going back even further in my story - 9,000 B.C.  Is it possible for you to make that calculation?

Sorry, that was my fault. I read it as 9000 BC but keyed in 900. I tried to calculate 9000 BC, but Starry Night only goes back to January 1, 4713 BC.   

Neither my Starry Night nor this site's star dome go back far enough either.  I could only go back 6,000 years as well.

Sorry about that,

L

Thanks guys for checking this out.  Do you have any suggestions for estimating the position of the Pleiades at such a date (9,000 B.C.E.)? 

Andy

Welcome to the discussion group, Andy.

Keep in mind that precession over a period of 11,000 years greatly shifts the apparent positions of stars on the celestial sphere.  Quite unlike today, the Pleiades in 9000 BC would have been a summer asterism that never rose very high for northern hemisphere observers.

According to my calculations, in 9000 BC the Pleiades would have been located near the winter solstice position of the Sun.  The brightest Pleiad, Alcyone, would have been at RA 18:01and Dec S 21.0°.  It would have been in opposition to the Sun around the time of the summer solstice, and would have culminated/transited about 40° above the southern horizon in the Canaries.  About one month after the summer solstice it would have culminated/transited around 22:00 (10 pm) local time.

The modern standard is to extrapolate backward the Julian calendar for ancient dates, even those before it was invented.  However, over great periods of time it gets well out of sync with the seasons because its 365.25-day year is not precisely accurate.  In 9000 BC the summer solstice would have occurred around August 24 in the Julian calendar, not late June.  Naturally, no one in your story would have been aware of the Julian calendar.

I’m an author too.  Good luck with your project.  Don’t be a one hit wonder here the way so many authors are.

Andy, I deleted my first response due to typos.  The version seen above is good.  I do want to comment on your statement that September or October would have suited you best for a present day setting.  Actually, the Pleiades culminate/transit the southern meridian around 10 pm local time in mid-December.  They would be somewhere above the horizon at that time for several months on other side.  Again, all of this only applies to the present day.  My previous post applies to 9000 BC.  Also back then, the Pleiades would have been above the horizon for a shorter period of time.

Centaur:

 

Andy, I deleted my first response due to typos. 

I wondered how long it would take you to correct the typos. I knew, as an author, that you wouldn't leave it the way it was.  

Did it even look like the Pleiades 11,000 years ago?

TeleNoob:

Did it even look like the Pleiades 11,000 years ago?

Apparently so.  I've written a computer program to illustrate.

That's quite surprising. I thought they would be alittle closer together. That bottom star has moved loads.

Centaur - this is all very helpful and I hope you will excuse my very limited knowledge of astronomy.  Here's a couple of follow-up questions to make sure that I understand what you said.  You're saying that the Pleaides would have culminated about one month after the summer solstice (Julian calendar) so that would be late September, right?  Then, you also said this would be 40 degrees about the southern horizon - thus my main character would have to be looking south? (this is problematic to my story right now since it's important that he is looking north)  Then, when you say the Pleaides "culminate" one month after the summer solstice, is that to say that they are first visible on the horizon at the summer solstice and slowly rise to 40 degrees?   My half-baked plan thus far was for the character to see the cluster pretty low over the horizon and make his way to an elevated vantage point above the sea.  So, I'm wondering if a little earlier than the culmination would be better for these conditions.  Finally, another aspect of the story is the Seventh Sister myth.  I've read that some of the Pleiades are not always visible to the naked eye (Calaeno and Sterope).  Does this seem realistic that one of these stars was not always visible way back in 9,000 BC?

 Thanks a million.  I'm hoping to put out a series of ancient historical, well really mythic fiction novels, so I don't want to be a one hit wonder!  Best of luck with your writing.

Andy

Andy, the type of calendar (Julian or any other) is irrelevant to the fact that the Pleiades in 9000 BC would have been in opposition to the Sun around the time of the summer solstice and would have culminated at 22:00 about a month later.  People in 9000 BC would not have been using the Julian calendar.  The fact that the seasons as measured by the Julian calendar would not have been in sync with the monthly dates with which we are familiar is an artifact of the modern astronomers’ standard of extrapolating the Julian calendar backward in time.  In your story I would not mention modern month names and would stick to seasonal relationships. 

Culmination refers to the moment that a star in its daily course is highest above the horizon.  Transit refers to the moment that a star crosses the local meridian, which is the line extending from the south point on the horizon upward toward the zenith.  Culmination and transit occur at virtually the same time. 

Currently, the Pleiades rise north of east, transit high in the south, and set north of west.  In 9000 BC they rose south of east, transited low in the south, set south of west, and would never have appeared anywhere near the north. 

Stars appear to circle through the sky over a period of about 23 hours and 56 minutes, due to the rotation of the Earth.  Each day they go through their cycle about four minutes earlier.  After one year they seem back to where they started.  That’s in the short run of human lifetimes; over thousands of years it gets more complicated. 

Opposition refers to the situation in which a star is opposite the Sun in the sky.  Thus at opposition a star would transit around local midnight.  About a month later it would transit around 22:00.  As each month passes the star transits about two hours earlier.  In 9000 BC in the Canaries, the Pleiades would have risen about 5.2 hours before transit, and set about 5.2 hours after transit. 

Stellar magnitudes (brightness) generally are not expected to have changed much over a period of only 11,000 years.  But a few people have argued that some of the Pleiades may have dimmed since antiquity.  My suspicion is that is principally due to our polluted skies (mainly light pollution). 

Are you aware that Homer in the Illiad and Odyssey has his characters using the Pleiades as a guide in navigation?   I hope my explanations make sense and have been helpful.

Hi Curt,

Yes this is all very helpful.  Thanks again.  Unfortunately, it does leave me in a bit of a quandry, plot-wise.  I'm going to have to figure out a reason for my character to be looking south.  There are other plot elements that need to be north of his position so I'll have to let this stew for awhile.

I'm not using modern day or Julian calendar months in the story.  It's just helpful for me to figure out what time of year things would be taking place as they translate to the fictional world I've created.

Yes, I'm familiar with Homer's work and I've done a lot of research on the ancient Greeks and the Pleiades.  Greek mythology is the inspiration for my story, and I'm creating an even more ancient world where the stories of their gods are retold.

Andy   

Glad to have helped, Andy.  Sorry that my information may have been somewhat discouraging.  A series of novels based on the origins of Greek mythology sounds quite interesting and may sell well.  The era and location cause me to suspect that your plot has something to do with the legend of Atlantis.  Not that I take it seriously, but a lot of people are eager to believe.  They may form a large base of potential readers for a series of well written books that inspire their imaginations. 

If your character must be facing north, you may want to consider the bright star Vega (magnitude 0.0) in the constellation Lyra.  Although not the case today, in 9000 BC Vega would have been circumpolar at the latitude of the Canaries.  That means it would have perpetually remained above the horizon circling the north celestial pole.  In 9000 BC Vega would have been at RA 12:42 and declination N 71.1° (18.9° from the pole).  It could have been considered the North Star during the centuries around 12,200 BC, when it was only a little more than 3° from the north celestial pole. 

Try using Cartes du Ciel

Oliver Tunnah:

That's quite surprising. I thought they would be alittle closer together. That bottom star has moved loads.

Oliver, the one that moved most noticeably is 26 Tauri.  It is a foreground star and not a physical member of the cluster.

That would explain that Curt, cheers. I still find it very surprising that the cluster hasn't moved that much, especially considering it's distance.