astronomy expert needed

There are two different questions here. How far north, and what time of year? If stars are too near the sun, they won't be visible at all. In the case of the Pleiades (not a constellation, but a cluster in the constellation of Taurus) they disappear from view entirely in Northern Hemisphere late spring / early summer. By late summer they're reappeared before dawn, but won't be visible until well after midnight. The geographical location won't make a difference as the Pleiades are visible way down into the Southern Hemisphere, but your MC will have to be getting up early or staying up late to do it.

AyJay said:

Here's another sticking point: my story is set in 9,000 BC. Stellarium only goes back to 4,000-something BC. Would the position of the cluster be dramatically different thousands of years back?

Andy

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Whoooooooaaaaaa, hold on. Big, big difference. There's a process called precession, which means the Earth does an odd wobble on its axis each 26000 years, which changes both where north is and where the sun is during summer. Taurus is a late Autumn / winter constellation now - the Pleiades look fantastic on a cold November night - but 11000 years ago it would have been a long way around the ecliptic.

A quick calculation (I'm not guaranteeing this, because I'm no expert) makes me think that the sun would have been in Taurus during autumn back then, which means it would have best been seen in spring, when in the tropics it would have appeared overhead, and if you wanted it in the evening, late spring would be good.

The shapes of the constellations would not have looked too different back than. A reasonable amateur astronomer would see notice some changes, but stars take a long, long time to change relative positions.

AyJay said:

Thanks for the info. Pri. I spent most of the day trying to track down this information. Even the astronomy experts were having trouble giving me an exact answer as their simulation programs don't calculate the position of stars beyond 6,000 years ago. I'm still pressing them for some guidance on estimating the position of the Pleiades cluster during the time period of my novel. But I guess the good news is that if no one can figure it out exactly, I won't have anyone calling me out if my storyline isn't 100% accurate.

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My feeling is that is won't be much at all. The Pleiades are a young star cluster, formed about 100 million years ago and 425 light years away. That means they're extremely young and far away. Constellation shapes change over time because constellations are shapes made of unconnected stars, some close and some far away. The ones nearer move through the sky faster than the further ones (you get the same effect travelling in a car - the roadside shoots by so fast you can't focus on the flowers while the house on a far hill stays in view for a minute or two). So Taurus will have changed a little in its shape, and nobody then would have called it Taurus anyway. Make up your own constellation name and it doesn't matter about constellation shapes.

The Pleiades will have looked more or less exactly as they do now, though, because all the stars formed at the same time and place. If they're close together now, we can be certain they were close together then. I remember a theory that one of the stars might have faded since classical times. It's called the Seven Sisters but most people, me included, can only make out six. With a telescope, on the other hand - wow.

To answer your original question: Yes.

-MM

Japanese name for the Seven Sisters - "Subaru" - yup, look at the logo.