Sir Norman Lockyer F.R.S. did some very interesting research on this topic and gave his expertise on this matter to a rather abstruse subject. His forte was solar research but this does not detract from his seminal deductions which are supported also by F.C.Penrose. His basic premise is that the rising and setting of a particular star or planet was taken into consideration when orientating the major axis of a particular temple. This research gives another indirect although extremely useful benefit ie. the probable date of the foundation of these temples and the dates of major modifications in their major axis due to the Precession of the Equinoxes. There are also dates of festivals given in past periods which would corroborate the choice of a certain star as it complements the dates and names of this festival.
" The inquiry , even in its present state, is sufficient to establish
a very high probability that the principal is a true one. There is nothing
vague about it. It has to be kept within very severe limits, and it holds
good nevertheless.
No stars can be accepted except from among the brightest, unless conspicuous
star groups may have been used instead. Again, of single stars, only such can
have been used for orientation in Greek temples which during a period
not incompatible with reasonable archaeology rose or set very near the line of
the sun's course at some period of the year; and a further restriction is this,
that the rising or setting must be just so far in advance of sunrise as to
enable the star to be seen from the adytum of the temple, and, at the same
time, not preceeding it by any longer interval of time than is necessary.
If, in addition to this, we find, as is frequently the case in the Egyptian
temples, and is not without parallel in Greece, that as the star to whose point
of rising or setting the axis of a temple was first aimed worked away from
its then position by precession, either the doorway of the temple was
altered, or a new temple founded alongside, so as to retain the desired observation;
and in every case of such new temple bieng so built it is found to have followed
the same cult as the original; if, in addition to this, in different provinces
temples are found of which the cult is known, and which are so planned as to
be able to use the same star- with such decided differences of orientation,
however, as were prescribed by lattitude and the local circumstances of the
surrounding heights- we obtain a further strong corroboration, and one that will
in many cases be sufficient to determine the cult, where this has not been
otherwise pointed out.
One further step requires to be taken to occupy the ground with perfect
confidence-viz. to inquire what analogy is there between the days of the month
when the sun would rise ushered in, as it may be said, by the temple's peculiar
star, and the days of the festivals as derived from historical sources. In this
comparison we must not expect a coincidence upon every point.
The date of the temple foundation in many cases is pre-Homeric, whilst the basis
of the historical account of the feast is probably post-Persic. There may have
been an interval of nearly 1,000 years between the two, so that there is room
for changes. Again, owing to their double system of reckoning months and years,
considerable variation in the dates given by Mommsen, whose authority I mainly
follow, is quite possible; and besides this, in some of the cases given below,
the orientation day, if I may so call it, may be in fault one or two days
for want of the exact particulars of the site for which I have made allusion."
From F.C.Penrose article in Nature Feb 25 1892 see full ref below:
The great temple at Eleusis is an example very much to this point. The
star which seems to have determined the orientation is Sirius, shining
as it rose at midnight along the axis of the temple on Sept14. The Eleusinian
mysteries are stated to have commenced on the 16th of this month. In this case
the sun was was not looked for; the weird light of the star was more likely
to have been reflected in these mysteries.
The star alpha Arietis is the brightest star of the first sign of the Zodiac
and would therefore, be very appropriate for a temple of Jupiter. The heliacal
rising of this star agrees both with the Olimpeium at Athens and that at
Olympia located at (37deg 38min N ). There is considerable difference in the deviation of the axes
of these two temples from the true east; but this is exactly accounted
for by the greater apparent altitude of Hymettus over the distant Mt
Pholoe.
This ancient Egyptian city was also a sister to its Boeotian compatriot.
The temple at Mycenae was built nearly north and south with an eastern
doorway.The star alpha Arietis, which suits the first, seems to point
out the dedication of this temple to Jupiter. The other is very
remarkable, and connects the Boeotian Thebes with the great Egyptian
city; the star was gamma Draconis. Thebes was called the City of the
Dragon, and tradition records that Cadmus introduced both Phoenician
and Egyptian worship.