Posted on 08/31/2004 8:42:25 AM PDT by SunkenCiv
At 8.45 on the morning of 15 April 136 BC, Babylon was plunged into darkness when the Moon passed in front of the Sun. An astrologer, who recorded the details in cuneiform characters on a clay tablet, wrote: "At 24 degrees after sunrise-a solar eclipse. When it began on the southwest side, Venus, Mercury and the normal stars were visible. Jupiter and Mars, which were in their period of disappearance, became visible. The Sun threw off the shadow from southwest to northeast." If present-day astronomers use a computer to run the movements of the Earth, Moon and Sun backwards from their present positions, like a movie in reverse, they find something very odd. The total eclipse of 15 April 136 BC should not have been visible from Babylon at all. The zone of totality should have passed over the Spanish island of Mallorca, 48.8 degrees west of Babylon-a difference of more than one-eighth of a complete rotation of the Earth, or 3.25 hours. The only explanation is that the planet's rotation has slowed since 136 BC, making the day longer. Of course, there are many other records of the ancients observing cosmic events, from supernovas to comets, but the value of these sightings to modern science is limited. Reports of eclipses, however, are in a class of their own. If the Earth has accumulated a change in orientation equivalent to an eighth of a turn in just over 2000 years, then we can infer that the day has lengthened by an average of a few milliseconds a century. This is an extraordinarily precise figure to deduce from historical records. In fact, it is without precedent.
(Excerpt) Read more at web.archive.org ...
There are at least three moons, maybe four identified so far. Cruithne serves as the site of the first interplanetary space battle in a recent sci-fi novel, US Marines versus asteroid miners.
ping
Fear and Awe: Eclipses Through the AgesOne of the earliest such incidents was recorded by Thucydides in his account of the Peloponnesian War, which took place in the 5th century BC. In the outbreak of the second phase of that war, the Athenians had attacked and blockaded the Sicilian city of Syracuse. After a two-year siege the Athenians were ready to pull out, but just before the departure signal was given there was a lunar eclipse which the Athenians took as a very bad omen for their departure. So the departure was delayed, and the delay allowed the Syracusans to break out of the siege, turning the tables on Athens and destroying the Athenian fleet and army. Athens was sent reeling, its democracy was overthrown, and Athens’ ultimate defeat resulted in the permanent decline of the gem of Greek civilization. There were, of course, many causes for the fall of Athens, but the lunar eclipse of 413 BC and the resultant military defeat that arose from it were key contributors to this turn of history.
by Wil Milan
18 January 2000The right hand of darknessThe inevitable clash came in the 7th century, in Northumbria. King Oswiu of Northumbria had established several new monasteries under the Celtic Church, but his consort, Queen Eanfleda, was a Kentish lady who belonged to the Roman Church. Their problem was in scheduling holidays: the Celtic Church determined the date of Easter according to an 84-year cycle brought by early Cretan missionaries, whereas the Roman Easter was fixed by the tables of Dionysius Exiguus, employing the 19-year metonic cycle (the near-coincidence between 19 solar years and 235 lunar months), so their Easter dates often differed. Eanfleda might be fasting on her Palm Sunday while Oswiu was feasting on his Easter Day. This inconvenience is often given as the reason that Oswiu convened the Synod of Whitby in 664, at which representatives of the two churches debated, competing for Oswiu's allegiance. Rome won, and that eventually led to the unification of the fiefdoms of the Angles, Saxons and Jutes to form the English nation... In 664, the zone of totality passed over northern Ireland, southern Scotland and northern England. It would have darkened all of Oswiu's monasteries. According to Daniel McCarthy and Aidan Breen of Trinity College, Dublin, the eclipse must have been a divine sign to Oswiu that he had erred in following the Celtic Church... Oswiu's conversion is the reason for the impending millennium, as well as for the existence of England. Several different Christian calendars were used in Oswiu's time, but our particular year numbering derives from the Dionysiac Easter tables adopted by the Venerable Bede in the early 8th century. Bede's mentors had been advocates of the Roman case at the synod. If the Celts had won instead, we might now be living in the year 2004, or 2037, or even 1967.
by Duncan Steel
I've heard recently on a cable astronomy program...that we are slowing down...and that the speed of light isn't what it once was, either!
BTW, eclipses repeat; a repetition is called a Saros:
qsaros ("sE@rQs) [Gr. r0qo| or raq¾| (Berossos), a. Assyro-Babylonian _Qr(u.] 1. Antiq. The Babylonian name for the number 3600, and hence for a period of 3600 years. 2. Astr. Adopted by modern astronomers as the name of the cycle of 18 years and 10 2 / 3 days, in which solar and lunar eclipses repeat themselves.
The notion expressed in quot. 1662, that the saros consisted of 3600 days, is due to the desire to rationalize the incredible statements of Berossos with regard to the lengths of the reigns of the antediluvian kings of Babylon. Other expedients for the same purpose were adopted by early writers on chronology.1613 Purchas Pilgrimage (1614) 54 Sarus with them is three thousand sixe hundred yeares.
1662 Stillingfl. Orig. Sacræ i. v. §4. 80 The learned Monks, Panodorus and Anianus,+make a Saros to contain 120. months of 30. dayes a piece.
This use is founded on the statement of Suidas (app. due to some mistake) that the length of the saros was 18 1 / 2 years.1812 Woodhouse Astron. xxxv. 353 The period of 223 lunations, called by the Chaldean Astronomers, the Saros.
1868 Lockyer Elem. Astron. iii. §18 (1879) 102 This period of 18 years 10 days is a cycle of the Moon, known to the ancient Chaldeans and Greeks under the name of Saros.
t'anks.
For the same reason an ice skater spins faster when her arms are pulled in the earth's rotation slows as the moon moves further away.The total Moon Earth Angular momentum is constant. This particular example however has many different solutions, for example if the spin inreased 21 hours it would also work. For that matter if you and or subtract any integer number of days it too would work. However Apollo left some mirrors on the moon that when lasers are focused on it gives a return beam that allows measurement to the moon within mere millimeters, and those measurements are increasing. Probably consistant with the numbers in this article too. (Tidal forces have already slowed the moon until it shows us the same face, it will eventually slow the earth so the moon sees the same face too)
For the same reason an ice skater spins faster when her arms are pulled in the earth's rotation slows as the moon moves further away.The change in the Earth's rate of rotation is attributed by that scientist to isostatic rebound due to the loss of the glacial ice thousands of years earlier, which fits with the ice skater example.
other lunar topics I've started:
A Celestial Collision
Alaska Science Forum ^ | February 10, 1983 | Larry Gedney
Posted on 09/15/2004 9:04:28 AM PDT by SunkenCiv
http://www.freerepublic.com/focus/f-chat/1216757/posts
It Came from Outer Space?
American Scientist ^ | November-December 2004 | David Schneider
Posted on 11/25/2004 5:13:07 PM PST by SunkenCiv
http://www.freerepublic.com/focus/chat/1288537/posts
When the Days Were Shorter
Alaska Science Forum (Article #742) ^ | November 11, 1985 | Larry Gedney
Posted on 10/04/2004 10:31:59 AM PDT by SunkenCiv
http://www.freerepublic.com/focus/f-chat/1234919/posts
this is what I just referred to in my reply to you in the "2029 impact" topic.
http://www.freerepublic.com/focus/news/1307719/posts?page=143#143
$180. one left in stock, order now!
The only explanation is that the planet's rotation has slowed since 136 BC, making the day longer.
Actually Edmond Halley was aware of this phenomenon and attributed it to a possible increase in the speed of the Moon. (DOH!)
If present-day astronomers use a computer to run the movements of the Earth, Moon and Sun backwards from their present positions, like a movie in reverse, they find something very odd. The total eclipse of 15 April 136 BC should not have been visible from Babylon at all.
Funny, I have a computer. I used a commercially available package "Starry Night" ($49.99 at Best Buy, not the professional edition) to run the Earth, Moon and Sun back to Babylon (32° 15' N, 45° 23' E) April 15, 136 BC and got a brief total eclipse runing from 8:33:45 to 8:36:16 local time (GMT+3.026 HR) which is about as close to 8:35 as you can get. When I set the location to Mallorca, Spain (39° 34' N, 2° 39' W), I get a partial eclipse beginning at 5:34 AM local time (GMT + 0), before sunrise at 5:46 AM and completely over at 6:23 AM.
I suppose if an astronomer had done it the results would have been different, I have the New Scientist's word on it.
Real astronomers, the kind that programmed Starry Night, for instance, unlike the kind in the New Scientist, are aware of the difference between time reckoned from the rotation of the Earth (Universal Time or UT) and a "uniform" time scale. The hypothetical uniform time scale is called "Ephemeris Time" (ET). Astronomers know how to account for the difference in UT and ET. I shouldn't be too hard on NS, they were using shorthand to say that if astronomers ignore the difference between ET and UT, they would get these results.
BTW, gotta give major props to Starry Night. The startlingly good agreement with observations, make me assume that the Babylonian Eclipse of 136 BC was one of the constraints they used to calculate the difference between ET and UT.
The difference between ET ( implemented as Terrestial Dynamical Time (TDT) today) and UT gives rise to leap seconds. That's a whole nuther thread!
Historical eclipses and Earth's rotationThe theme of my lecture thus seems apt. For more than three centuries – commencing with a paper by Edmond Halley in 1695 – the study of ancient and medieval observations of eclipses has provided valuable information about the Earth–Moon system. Today, early eclipse observations are the principal source of data for information on long-term variations in the Earth’s rate of rotation... Variations in the MSD are the subject of this lecture. Following decades of speculation, Sir Harold Spencer Jones in 1939 conclusively demonstrated that even the MSD is not an ideal unit; the Earth in its diurnal rotation is a very good timekeeper but is by no means perfect. Astronomical observations reveal fluctuations in the length of the day (LOD) at the millisecond level; using historical observations these fluctuations can be traced back more than 2500 years... An additional long-term mechanism is post-glacial isostatic compensation; the ongoing rise of land that was glaciated during the last ice-age produces a slow diminution in the moment of inertia of the Earth, with consequent decrease in the LOD. Seasonal and annual fluctuations have been mapped in detail only since the introduction of Atomic Time (AT) in 1955. Decadal variations in the LOD can be traced over the last four centuries or so (i.e. the telescopic period), mainly using occultations of stars by the Moon.
F Richard Stephenson
(PDF)
September 1752
(Great Britain and Dominions)Sun Mon Tue Wed Thu Fri Sat 1 2 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Long as Mrs. Lonesome doesn't find out, then I really will be Lonesome.
Historical Eclipses:
http://hbar.phys.msu.ru/gorm/atext/histecl.htm
A Larger Sun During The Maunder Minimum
William R. Corliss
(Ribes, E., et al; "Evidence for a Larger Sun with a Slower Rotation during the Seventeenth Century," Nature, 326: 52, 1987.)
http://www.science-frontiers.com/sf051/sf051a05.htm
My company has a research library, which works with university libraries. (I've gotten books from libraries in California through them. Usually loans are from Zoo Mass. or MIT.) Hard to explain it as work related and interlibrary loans are good for two-four weeks.
Minuteman Library System (most of the public libraries in Eastern Mass. and some colleges) does not have it.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.
