Astronomy in Israel
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MEGALITHS
Prehistoric astronomical activity is represented by a Stonehengelike
megalithic circle and "Observatory" at Rujm-el-Hiri, near Yonathan
in the Golan, the Westernmost sector of the historical Bashan plateau dating
from the IIIrd Millenium BC. Star worship is mentioned in the Old Testament
as beeing common among the Canaanites, but the Bashan inhabitants who built
that Golan megalithic circle antedate the Canaanites. Very little is known
about them and the presumably religous role of their edifice. To the IIIth
Century BC Israelitis, they appeared as the work of giants (Refa'im, also
Anakim, Emim, Zuzim), and this is probably the source of the legends about
races of giants that had lived in Eretz-Israel prior to the Israelite conquest
- including the characterization "a remnant of the giants" for Og,
King of Bashan, in Deuteronomy and Joshua. Indeed, the Rujm-el-Hiri circle
is just one among many megalithic remains in the Bashan, probably at the
origin in Greece and England (the "Giant's Dance" = Stonehenge).
ASTRONOMY IN THE MISHNA
The Israelitis' abstract monotheism and their centering of intellectual
creativity on ethical issues were detrimental to a natural development
of observational science, as did happen in Sumeria or Greece. However,
the requirements of agriculture induced a cycle of holidays that were incorporated
in time into Judaism and were given Ethnical or National religious significance.
There thus developed a need for an understanding of the recurrence of seasons
and for a synchronized calendar fitted to Solar, Lunar and Sidereal time.
Several of the Mishnaic scholars were versed in Astronomy, such as the
"Tannaim" Yehoshua ben Zakkai, the Patriarch Gamliel II and
in particular Yehoshua (=Joshua) ben Hananiah. In the tractate Horayoth,
dealing with errors of Justice, the following anecdote is related:
"Rabbi Gamliel and Rabbi Yehoshua went together on a voyage at sea. Rabbi
Gamliel carried a supply of bread, Rabbi Yehoshua carried a similar amount
of bread and in addition a reserve of flour. At sea, they used up the entire
supply of bread and had to utilize Rabbi Yehoshua's flour reserve. Rabbi
Gamliel then asked Rabbi Yehoshua - "Did you know that this trip would
last longer than usual, when you decided to carry this flour reserve?"
Rabbi Yehoshua answered - "There is a star that appears every 70
years and induces navigational errors. I thought it might appear and cause
us to go astray." Rabbi Gamliel then exclaimed "You are so knowledgeable
and you nevertheless have to travel to make a living?" Rabbi Yehoshua
then answered bitterly - "How come you are so surprised? Do'nt you know
that two of your own students Rabbi Eliezer Hisma and Rabbi Yehohanan ben
Gudgada who are so smart that they can tell you how many drops there are
in the ocean, have neither bread to eat nor clothes to wear?"
This observation is generally interpreted as relating to Halley's Comet,
with a period aproximating 76 years. Observing a comet's periodicity, with
such a long period, requires records covering many centuries; it is possible
that the Mishnaic scholars did inherit such records from the Great Knesset
scholars (before 300 BC) who received them during the Babylonian exile
(586-537 BC) from the "Chaldeans" (i.e. from Sumer, Akad etc. going back
to the IIIrd Millenium BC). Indeed, the Hebrew agricultural names of the
months were replaced by Sumerian and Akadian names after the Babylonian
captivity. However, there is perhaps a difficulty with the dates: Rabbi
Yehoshua was born in 35 AD and died in 117 AD. Rabbi Gamliel died in 115
AD. The only appearance of Halley's Comet in the interval 55-155 (when
Yehoshua was older than 20), is in 66 AD. Rabbi Gamliel was younger then
Rabbi Yehoshua and it has been argued that if he was 20-25 years old, it
is doubtful whether he could have had students at the time. Still, this
is not a strong argument, as Rabbi Gamliel II was also the hereditary Patriarch,
and may have had students attached to him formally from the moment he was
appointed head of the Sanhedrin.
Philippe Veron has, however, come up recently with a different identification
of Rabbi Yehoshua's star, and argues that this was the variable Mira.
Mar Samuel, who became around 220 AD the Dean of the Talmudic Academy
of Nehardea in Babylonia, was an astronomer who could calculate and adjust
the calendar with great precision, intercalating an extra month or reassigning
the length of a month. The prescriptions for the calendar adjustments were
written down in a special Baraita. They include the 19 years synchronization
cycle to this very day in the Jewish Calendar.
SPAIN AND PROVENCE
Science spreads by convection. When Khushru Anushirvan, Sassanid Emperor
of Persia, signed a ten year truce with Justinian of Byzance, he ensured
the continuity of science by requesting that the teachers of the recently
abolished Academy of Athens be transferred to Persia. In his fanaticism,
Justinian was then trying hard to put an end to Judaism at the sametime
eradicating Neo-Platonicism and what was left of Greek science. The Neo-Platonicists
settled in Mesopotamia under Persian rule, and their school was already
flourishing when Persia was conquered by Islam. Mathematics and Astronomy
thrived (e.g. Omar Khayyam, whose Rubayat was just a hobby, his professional
creativity having yielded methods for solving factorizable cubic equations
etc.) and spread all over the new Mohammedon Empire. The Jews were active
participants, and the first Arabic-languate treatise on the Astrolabe was
written by the Jew Joel, known as Masha-Allah of Basra (Iraq)
around the year 800. This is the treatise that was translated into English
by Geoffrey Chaucer ("The Treatise on the Astrolabe") around 1380,
from a prior Latin translation. Masha-Allah also wrote a book on Lunar
and Solar Eclipses, that was later translated into Hebrew by Abraham
Ibn Ezra ("Sefer be kadrut ha levana ve ha shemesh"")
Sind ben Ali, a heretic Jew, was the main contributor (~830) to
the astronomical tables of the Caliph Maimum. The scene now shifts to Spain,
where Abraham bar Hiyya Hanasi ("The Prince") of Barcelona (d. 1336)
improved on these tables, using calculations performed by the Arab astronomer
Al-Battani (d. 929). Abraham bar Hiyya was a prominent mathematician and
astronomer, and wrote famous textboks in both fields. He introduced Europe
to (Arab) trigonometry in his "Treatise on Mensuration and Calculations".
The Hebrew was translated by Plast of Tivoli into Latin in 1145 and his
book served as main source material for that later work of Leonardo Fibonacci
of Pisa. In Astronomy, his book "The Shape of the Earth" is based
upon the Ptolemaic system, contains a roughly correct estimate of the distance
to the Moon (but the wrong distance to the Sun). The principles for Calender
intercalation make up yet another book.)
His student, Abraham Ibn Ezra (1089-1164), poet, philosopher, Biblical
commentator and Astronomer, spent the last part of this life travelling
in Italy and France, ending up in Eretz-Israel. He continued the publication
of tables, mostly on the movement of the planets. The "Toledo Tables"
were compiled by 12 Jewish astronomers led by the Cordovan Arab astronomer
Ibn Arzarkali ("Azarchel"). The Latin version (translated by John of Brescia
and Jacob Ibn Tibbon) was further improved in 1272 by a group of astronomers
led by Isaac Ibn Said, and is known as the "Alphonsine Tables".
Rabbi Moshe ben Maimon's (=Maimonides) main contribution to Astronomy
in his complete rejection of Astrology (1194). He is is unique,
throughout the Centuries, in making this clear-cut. Remember that Kepler
was still drawing horoscopes! Perhaps this should justify a visit to Maimonides'
tomb in Tiberias.......
Rabbi Levi ben Gershom ( = Gersonides, also Maestre Leo de Bagnols,
Maestre Leo Hebraeus; 1288-1344), was one of the greatest of Medieval astronomers.
He lived in Provence, mostly at Orange. As a mathematician, he rediscovered
the law of sines and published a sine table, correct to the 5th decimal.
As an astronomer (he wrote 136 "chapters"!), he is the first to have relied
on his own observations (in his studies of eclipses) rather than on Ptolemy's.
He invented "Jacob's staff", a navigational instrument which was
widely used for 3 centuries, and was the first person kown to have used
a Camera Obscura for his observations.
Rabbi Levi is also the first scientist to derive more realistice estimates
of the distance to the fixed stars. Ptolemy's estimate was of the order
of 10-5 light years ( a million
times smaller than the distance to the nearest star), whereas Rabbi Levi
reached a figure of about 105 light
years, 10 times our present estimate for the distance to an average star
in the Galaxy. Gersonides was also one of the greatest Medieval philosophers
and published Commentaries to the Bible.
The Zohar, a compilation of Jewish mystic writings drawn in Spain
in the XIIIth Century anticipates Copernicus by stating that "the whole
earth spins in a circle like a ball; the one part is up when the other
part is down; the one part is light when the other is dark; it is day in
the one part and night in the other".
Jewish astronomers played a key role in the theoretical preparation of
the great voyages of discovery in the XVth Century. Judah Cresques,
forced to adopt Christianity in the massacres of 1391, later became the
Director of the Prince Henry of Portugal's ("The Navigator") Nautical Academy
of Sagres. Abraham Zacuto ("Zacut", 1452-1515) worked first
at Salamanca but moved to Portugal after the expulsion from Spain. As Court
Astronomer to Kings John II and Manuel I, he prepared the voyage of Vasco
da Gama (1496) and supplied instumentation (include his newly perfected
copper astrolabe), improved tables, charts, intruction and briefs. He developed
the first copper astrolabe. His very precise predictions of eclipses were
used by Columbus to threaten the natives at a dangerous moment. Like all
Jews, Zacut had to flee Portugal in 1497 and went to Tunis. He died in
Eretz-Israel.
MODERN TIMES
The XVI-XVIIth Centuries were centuries of Jewish sufferings, and contributions
to Astronomy are less prominent, except perhaps for the Herschel family,
of Jewish origin. It was only when Alexander von Humboldt became President
of the Prussian Academy of Sciences, that he abolished the requirement
of a Christian Oath by a Professor at his ordination. Karl-Gustav Jacobi
was the first Jew who did not have to abjure his faith to become a Professor.
The oath was re-establised by von Humbold successor, but it was no more
in existence when Einstein, Minkowski and Schwarzschild were ordinated.
MODERN ISRAEL
Until 1965, observational astronomy was entirely a matter of amateurs.
In that year we started astronomical research at Tel-Aviv
University, and by 1969 we had a Department
of Physics and Astronomy, still the only one in the country in 1982.
In 1971 we inaugurated, with the help of the Smithsonian Astrophysical
Observatory, the Florence and George
Wise Observatory at Mizpe-Ramon (altitude 950m.) in the Negev.
The telescope is a 40" Wide Angle Richtie-Chretien reflector. European
astronomers have often used the instrument. The most important observations
at the Wise Observatory have been:
the first optical identification of an X-ray pulsar, Hercules X-1 (J. and
N. Bahcall, 1972)
the first direct verification of Whipple's conjecture about comet-tails
being composed of water (P. Wehinger and S. Wycoft, together with G. Herbig
at Lick Observatory and G. Hertberg and H. Liu in Canada, 1974)
the discovery of Sodium and Sulphur clouds around Jupiter, along the orbit
of its satellite 10. (Y. Mekler, A. Eviatar and I. Kupo, 1974)
the precise observation of a recurrrent Nova leading to a better understanding
of the Nova mechanism (N. Brosch, E. Leibowitz, 1978)
the discovery of the 13-day period in SS433 (E. Leibowitz, T. Mazeh, in
coll. with the University of Oregon, 1979).