Willie R. Meghar wrote:
Once upon a time (if memory serves) there was a discussion on saa
concerning the missing Pleiad.

Back in the days before beef stew (or somewhat more recently) the
average eye, on an average night, could see 6 naked eye stars in the
Pleiades star cluster. Since this cluster was also referred to as the
*Seven Sisters*; there was speculation concerning the fate of the
missing Pleiad.

In my own experience, either 6 or 9 of the named stars can be seen
with the naked eye. If conditions are good enough to see 7, I'll also
see two more.

Fast forward to today. I recently read about the Pleiades in yet
another book. An illustration showed the 9 brightest stars along with
their names. The text pointed out the seven sisters as well as the
two parents. At that point a thought crossed my mind.

On those nights when I could see 9 stars I was seeing the seven
sisters and the two parents. Might it be that before the
proliferation of outdoor lighting, on a good night, the average
observer could see the nine named stars? Might it also be that those
observers were aware of the distinction between the seven sisters and
the two parents? If so, when they spoke of seeing seven Pleiades they
were referring only to the sisters since the parents, though present
and visible, were not sisters. Might this clear up the case of the
(not so) missing Pleiad?

Willie R. Meghar

Also keep in mind that some eyes are better than others.

Historical Perspective
http://www.ast.cam.ac.uk/~ipswich/Ob...g_Proj/POP.htm

Many of the great observers of history counted the number of Pleiads
visible to the naked eye. Some of these observers had exceptional
eyesight, and of course observed without the curse of light pollution
that we suffer from so badly today. The most impressive historical
observers of the Pleiades are as follows:


Maestlin (1550-1631; Kepler's tutor) claimed to see 14 and mapped 11
before the invention of the telescope.

Carrington (1826-1875) & Denning (1848-1931) counted 14.

Miss Airy (daughter of G B Airy) counted 12.

William Dawes (1799-1868) counted 13.

One record of the modern era is by O'Meara who claimed to discern 17
Pleiads by naked eye in 1978 at Cambridge, MA, USA.