Archive for the ‘Astronomy’ Category

The earth may be spherical but the universe is (largely) flat

May 1, 2018

The earth’s orbital plane is not quite flat. The ecliptic is currently reducing by about 1.4 degrees over 100,000 years.


 

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Dwarf planets demand full planetary rights and an end to discrimination

March 26, 2018

The five dwarf planets (Ceres in the asteroid belt, and the trans-Neptunian planets led by Pluto)) have demanded that discrimination against them  cease immediately and that they be afforded full planetary rights along with the “Big 8”. Over 150 bodies are trans-Neptunian planets (TNPs) but only four are recognised as dwarf planets (Pluto, Eris, Haumea, and Makemake).

A spokesman for the TNP’s complained that the International Astronomical Union was being blatantly unfair against the “small and the distant” and was guilty of violating the fundamental, God-given rights of every planetary body. “The members of the IAU are all earthlings and small-minded and biased”, he said. “It is a travesty that even a planet as near the Sun as Ceres could be treated with such disdain”, he continued. He claimed that actually there were over 250 TNP’s but many had yet to be contacted. He accused the IAU of gross geocentrism. “It is morally unacceptable to deny these ancient planets their full rights and to stigmatise them by calling them dwarfs”. “Do we not all orbit the same Sun?”, he asked. ”

The International Astronomical Union denied any discrimination. A spokesman angrily refused to comment when accused of being geocentric. He denied that the IAU was steeped in dwarfism.


 

Why does the earth rotate in 24 hours? It’s just magic

June 26, 2017

The rotational speed of a planetary body around its own axis is primarily set by the angular momentum the mass of matter making up the body had when it first coalesced into a planet. What determined that initial angular momentum is unknown. All known effects thereafter (mainly tidal and all fundamentally gravitational effects) slow this rotation. For the last 3,000 years the earth’s rotation has been slowing down to cause the day to lengthen by about 2 milliseconds per century.

Currently the solar (siderial) day has a mean value of about 2 milliseconds greater than 86,400 seconds while the stellar day (relative to the fixed stars) has a mean value of about 86, 164 seconds.

But we have no real understanding of why it is what it is. We can observe that the day length on the planets are:

We have no real explanation for why Mercury and Venus rotate as slowly as they do. But it is believed that at coalescence the angular momentum must have been similar but subsequent gravitational effects (solar gravitation effects on Mercury and “tidal” effects on Venus and it’s thick atmosphere) have drastically slowed the rotation. But this is mainly speculation. It is now thought that even distant Jupiter may be having an effect on Mercury’s orbit and spin.

Mercury spins three times on its axis for every two revolutions around the sun. It was natural to assume the sun was influencing Mercury’s spin. Now scientists have learned that distant Jupiter – largest planet and second-largest body in our solar system – also may also be influencing Mercury’s orbit and spin, which is more complex than scientists realized.

Among the outer planets there is a very rough correlation between the size of the planet and rotational speed. But there are no apparent correlations with mass, density, distance from the sun or any other parameter. All we can say about any planet’s spin is that it depends on the angular momentum of the material which coalesced to form the planet and thereafter it changed due to collisions as the planet formed, subsequent gravitational interactions with other bodies, and tidal interactions.

SciAmIn our solar system, the giant gas planets (Jupiter, Saturn, Uranus, and Neptune) spin more rapidly on their axes than the inner planets do and possess most of the system’s angular momentum. The sun itself rotates slowly, only once a month. The planets all revolve around the sun in the same direction and in virtually the same plane. In addition, they all rotate in the same general direction, with the exceptions of Venus and Uranus. These differences are believed to stem from collisions that occurred late in the planets’ formation. (A similar collision is believed to have led to the formation of our moon.)

Planetary spin (Pinterest)

The laws of physics (as we know them) did not apply at the Big Bang singularity. All the energy (dark, imaginary and real) in the universe and all the momentum in all the materia (dark or otherwise) making up the universe was determined in the singularity when the laws of physics did not apply. How the Big Bang caused matter to gain spin in the first place is also unknown. So the simple answer to why earth’s day is 24 hours long (and why any planet’s rotational speed is what it is) is that we haven’t a clue.

It’s just magic.


 

The Big Bang theory is just another Creation myth

December 16, 2015

I was listening to some lectures on Relativity to celebrate the 100th anniversary of Einstein’s General Theory of Relativity. What struck me, again, was how claims to be entirely rational all contain an element of magical belief.

The concept of “time” is not, I think identical to “the elapse of time”. Suppose that “the elapse of time”, along with space-time and all matter and all energy, came into existence only with the singularity called the Big Bang. Then the Big Bang theory and the Genesis Creation myth are similar in that both ultimately rely on the invocation of Magic. Genesis labels the Magic as “God”. The Big Bang theory either assumes that the singularity just Magically came to be, or claims it was inevitable and due to the laws of quantum physics, which just Magically came to be. Both Genesis and the Big Bang theory begin with “In the beginning….”, which inherently contains the assumption of a concept not only of “time”, and the existence of a “before” and an “after” but also the concept of being “timeless”. The state of “before” applied to “the beginning of time”, can only be a timeless state (stasis) or a state where time exists but does not elapse.

Magic is to the Big Bang theory what God is to the Genesis Creation myth.

Physicists (cosmologists) claim that the Big Bang occurred 13.8 billion years ago (definitely less than 15 billion years ago according to Hawking), but I question that. Physicists are being illogical here. The existence of a singularity on the time axis itself requires that a “speed of time” exist. Since, at the singularity the “speed of time” was – must be – zero, it must have subsequently, in the first apparent moments after the singularity, accelerated to the current rate of elapse of time. So the 13.8 billion years ago is only an apparent, perceived point along the time axis where eal time actually goes back to infinity (and must do so).

The Big Bang does not, apparently, mathematically permit of a time older than 13.8 billion years. Magical eal time, of course, goes back to infinitely long ago. All can be resolved merely by accepting that ℜeal time elapsed at zero rate at the Big Bang and then gradually built up to the rate of elapse we are subject to now.

There are those (Stephen Hawking) who say that anything before the Big Bang is indeterminate and indeterminable because all the laws of physics, and even the conservation of matter, break down at a singularity. Therefore, Hawking claims, “time” starts with the Big Bang. He claims that whereas the Genesis Creation myth requires the external imposition of a God, the Big Bang theory is just an extrapolation backwards of the “dynamical laws that govern the universe” and is therefore “intrinsic to the universe, and is not imposed on it from outside”. Really? And pray by what Magic did the “dynamical laws of the Universe” come to exist or to apply? Hawking may be an atheist but he invokes Magic whenever he refers to the singularity of the Big Bang theory (even if he claims not to).

There are others (Alex Filippenko) who claim that quantum theory is the cause of the Big Bang and that the laws of physics are sufficient to bring about the singularity. But Filippenko is a little more honest than Hawking and admits that the “laws of physics” are in themselves Magical.

“The question, then, is, ‘Why are there laws of physics?'” he said. “And you could say, ‘Well, that required a divine creator, who created these laws of physics and the spark that led from the laws of physics to these universes, maybe more than one.'”

“The ‘divine spark’ was whatever produced the laws of physics,” Filippenko said. “And I don’t know what produced that divine spark. So let’s just leave it at the laws of physics.”

What we don’t know lies in the Space of Ignorance. One Magic (and there are surely as many Magics as humans have ignorances) is that which transcends perceived “time” and applies even across singularities such as the Big Bang. But this, let’s call it, “Creation Magic” – like all Magics – lies in the Space of Ignorance. And if some people wish to do so, they can give this Magic (which we are ignorant of)  the label of “God” or of “Nirvana”.

Related:

The fundamentals of physics are just magic

Dark energy and dark matter are just fudge factors for cosmic models that don’t work

Physics and cosmology are more magical than alchemy as dark energy goes phantom

It may be small but Pluto is still a planet

July 13, 2015

It orbits the Sun. It has five moons. It is the tenth most massive object orbiting the Sun. It is not that Pluto is not a planet, but that there are many more planets than the “big ten”. The asteroid belt and the Kuiper belt objects are all also planets. Inventing new definitions and calling them “dwarf planets” or “planetoids” doesn’t change the fundamentals.

The International Astronomical Union (IAU) defines a planet thus:

A planet is a celestial body which:

  1. is in orbit around a Star,
  2. has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
  3. has “cleared the neighbourhood” around its orbit.

Calling Pluto a “dwarf planet” rather than a “planet” has nothing to do with its properties or the properties of the Sun. It is not even a matter of language or semantics. It is merely for the convenience of a bunch of lazy astronomers who were afraid of having too many planets to classify.

Ultimately it is just a matter of usage. For me any celestial body orbiting another is and remains a planetary body. And every body which orbits the Sun directly (and not by virtue of orbiting a planetary body first) is a planet. Every asteroid is a planet of the Sun. Jupiters moons remain planets of Jupiter. And that makes Pluto a planet. New planets may well have been found in the Kuiper belt – but Pluto remains a planet for me, in spite of the failings of the IAU.

“Let there be cesium” and there was a leap second

June 28, 2015

On 30th June 2015 at 23:59:60, a leap second will be added before 1st July 2015, 00:00:00 because the difference between Coordinated Universal Time (UTC) and Universal Time (UT1) would have reached 0.9 seconds. Universal Time also known as Astronomical Time is based on the Earth’s rotation around its own axis, which determines the length of a day. Since 1972, 25 leap seconds have been inserted to synchronise these two clocks and this leap second will be the 26th. The differences are so irregular that the need for a leap second cannot be predicted more than about 6 months in advance.

The leap second is for synchronising the two clocks and not – directly – for compensating for the slowing down of the earth and the lengthening of the day. That adds about 1 second every 58,800 years (1.7ms per century). Since modern humans arrived on the scene some 200,000+ years ago the length of the day has increased by about 4 seconds.

International Atomic Time (TAI) is the “standard” used to synchronise the other two clocks and is built up by combining the output of some 200 highly precise atomic clocks worldwide and where the second is defined by the resonant oscillation frequency of cesium 133.

Atomic clocks use the second as the base unit and hours, days and years are taken to be multiples.

“The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom.”

The wise men of our age believe (they cannot know) that this resonant frequency of the cesium 133 atom will remain “stable” for millions of years and is far more stable than the period of rotation of the irregular orbit of the earth around the sun or the even more irregular (and slowing) rotation period of the earth on its own axis.

All we measure, or try to measure, are periods of time – provided of course that time exists. Cesium would not have come into existence until about 3 minutes after the Big Bang, but time, presumably, began with the Big Bang. Initially there was only hydrogen and then came Big Bang Nucleosynthesis (BBN), which after about 10 seconds (cesium 133 seconds, though cesium still didn’t exist) started producing helium. The heavy elements came about 3 minutes after the BB and after about 20 minutes BBN ceased. Light would have been created as soon as the fusion of hydrogen started with the BB itself.

Rephrasing Genesis

The Big Bang was the Beginning and then came Fusion. The expanse was without form and void, and dark energy was over the face of the deep. And the Spirit of Gravity hovered over the face of the aether. And Gravity said, “Let there be Coalescence” and the stars of the heavens came to be. “Let there coalesce a Sun” said Gravity, and so there was light. “Let coalescence proceed” and under Gravity came the earth bathed in the light of the Sun. And the light was good. 

And the rest is history.

 

Sea surface temperature and the 18.6 year lunar nodal cycle

October 15, 2014

There is a growing body of scientific papers (some reported in my post here) which show long period connections between the 18.6 year lunar nodal cycles and sea level, tidal sedimentation, tidal mixing, sea surface temperature, Arctic climate and even drought. The mechanisms by which these influences are transmitted are hypothesised but are not known.

Compared to solar cycles the lunar cycles are not well known:

The lunar nodal cycle is not something that is very well known but it is another celestial cycle which is clearly not to be ignored. Naturally the IPCC takes no notice of solar cycles, planetary cycles or lunar cycles and all these are lumped into what could be considered “natural variability”.

(Sourced from Wikipedia)

The lunar orbit is inclined by about 5 degrees on the ecliptic. The moon  therefore can lie up to about 5 degrees north or south of the ecliptic. The ecliptic is the plane of the apparent path of the Sun on the celestial sphere, and is coplanar with both the orbit of the Earth around the Sun and the apparent orbit of the Sun around the Earth.

File:Lunar eclipse diagram-en.svg

Lunar eclipse orbital diagram: wikipedia

The lunar nodes precess around the ecliptic, completing a revolution (called a draconitic or nodical period, the period of nutation) in 6793.5 days or 18.5996 years.

The effects of the 18.6 year lunar nodal cycle on climate on tides and geological sediments and on weather and climate have long been of interest (though not apparently for the IPCC).

The lunar nodes and the nodal cycles were known even to ancient astronomy (Greek, Hindu, Tibetan…) and has found a place in both Eastern and Western astrology. Since astrology is not considered “scientific”, suggestions that the lunar nodal cycle has any impact on the earth’s geology and climate are very often treated with ridicule. Yet the undoubted lunar effects on tides and tidal sedimentation and (therefore) geologic events are not disputed. The nodal period also controls when eclipses can occur.

Eclipses occur only near the lunar nodes: Solar eclipses occur when the passage of the Moon through a node coincides with the new moon; lunar eclipses occur when passage coincides with the full moon. A lunar eclipse may occur if there is a full moon within 11° 38′ (Celestial Longitude), of a node, and a solar eclipse may occur if there is a new moon within 17° 25′ of a node.

It is not surprising that the ancient astrologers/astronomers attributed many effects to the lunar nodes and the nodal cycles:

In Hindu astronomy, the ascending node is called Rahu and the descending node is called Ketu. Rahu and Ketu are thus the north and the south lunar nodes. Rahu represents the severed head of an asura, that swallows the sun causing eclipses. Times of day considered to be under the influence of Rahu are considered inauspicious even today in many parts of India (for weddings, starting journeys …..)

A new paper considers the effects of the 18.6 year lunar nodal cycle on Sea Surface Temperature (SST) and the Pacific Decadal Oscillation (PDO).

S. Osafune, S. Masuda and N. Sugiura, Role of the oceanic bridge in linking the 18.6-year modulation of tidal mixing and long-term SST change in the North Pacific, Geophysical Research Letters, DOI: 10.1002/2014GL061737

HockeyShtick reports:

A paper published today in Geophysical Research Letters finds a “significant contribution” of the 18.6 year lunar-tidal cycle to “wintertime sea surface temperatures near the center of action of the Pacific Decadal Oscillation [PDO] in the eastern Pacific,” and that

“This result supports the hypothesis that the 18.6-year tidal cycle influences long-term variability in climate; thus, knowledge of this cycle could contribute towards improving decadal predictions of climate.” [which IPCC climate models do not incorporate]

The approximately 60-year long Pacific Decadal Oscillation [PDO] in-turn profoundly affects global climate and interacts with other ocean and atmospheric oscillations. A very simple climate model based solely upon the sum of the sunspot integral, Pacific Decadal Oscillation [PDO], and Atlantic Multidecadal Oscillation [AMO] explains 96% of climate change over the 20th century: …..

 

Paper Abstract:The impact of the 18.6-year modulation of tidal mixing on sea surface temperature (SST) in the North Pacific is investigated in a comparative study using an ocean data synthesis system. We show that remote impact through a slow ocean response can make a significant contribution to the observed bidecadal variation in wintertime SST near the center of action of the Pacific Decadal Oscillation in the eastern Pacific. A comparative data synthesis experiment showed that the modified SST variation is amplified by bidecadal variation in the westerly wind. This relationship between SST and wind variations is consistent with an observed air–sea coupled mode in the extratropics, which suggests that a midlatitude air–sea interaction plays an important role in enhancing the climate signal of the 18.6-year modulation. This result supports the hypothesis that the 18.6-year tidal cycle influences long-term variability in climate; thus, knowledge of this cycle could contribute towards improving decadal predictions of climate.

I am of the opinion that climate is predominated by solar effects which are mediated primarily by the oceans over multidecadal periods and only over shorter periods by the atmosphere. And if lunar nodal cycles influence the tidal flows and tidal mixing then they will also influence the climate – also on the decadal scale.

We dance to a celestial music and the moon provides the variations on the climate themes set by the sun.

 

Poltergeists on Mars

January 21, 2014

Mysterious forces and poltergeists are at work  on Mars (which in due course will be found not to be so mysterious after all). But stories about moving rocks, and possible aliens are not new. The latest however is just doing the rounds based on the pictures SOL 3528 and 3540.

Rock appears mysteriously in front of Mars Opportunity rover

Rock appears mysteriously in front of Mars Opportunity rover

(Phys.org)The lead scientist for NASA’s Mars rover exploration team (Steve Squyres) has announced that recent images beamed back by the Opportunity rover show a rock sitting in a place nearby where there wasn’t one just twelve days prior. The image, he says, has caused quite a commotion with the rover team as possible explanations for the sudden appearance of the rock are bandied about. The announcement was part of a meeting at California Institute of Technology to celebrate a decade of service by the tiny rover. …… 

….. How it got there has NASA’s best scratching their heads. Thus far, they have two main likely explanations: either the rock was tossed to that spot after a meteorite impact nearby, or far more likely, it came to rest there as a result of clumsy maneuvering by Opportunity itself. The rover is having trouble getting around these days as one of its actuators has failed. This means one wheel winds up scrapping the ground during turns, producing what Squyres described as “chatter” which he said could have caused some debris to be flung to where the rock is now.

But these stories have been appearing since – at least – about 2009 (based for example on pictures SOL 1833 onwards). Moving rocks on Mars have a long history of fanciful – and some not so fanciful – notions. A whole bunch can be found here and here. But it would seem that most of the conspiracy theories and “Life on Mars” stories are connected to the selling of particular books.

As far as stories are concerned, the first ever fictional account of Mars was probably Across the Zodiac (1880) by Percy Greg. But for me, The War of the Worlds (published in 1898) by H. G. Wells  and Edgar Rice Burroughs and his Martian Trilogy – published between 1912 and 1943 and which I first read in 1959 – are not easily surpassed.

An infinite and timeless universe measured with an accuracy of 1%!

January 10, 2014

A new paper has been capturing some headlines. It is all completely beyond me and while the Abstract – written presumably in English – may be perfectly intelligible for an astronomer or a physicist, it is totally incomprehensible for me. But some of the quotations in the accompanying press release – which were picked up and reported widely in the mainstream media (here and here for example) – sounded strangely illogical.

from the Press Release

  • Today the Baryon Oscillation Spectroscopic Survey (BOSS) Collaboration announced that BOSS has measured the scale of the universe to an accuracy of one percent.
  • “One-percent accuracy in the scale of the universe is the most precise such measurement ever made,” says BOSS’s principal investigator, David Schlegel, a member of the Physics Division of the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab). 
  • … the BOSS results suggest that dark energy is a cosmological constant whose strength does not vary in space or time. 
  • …. the BOSS analysis “also provides one of the best-ever determinations of the curvature of space. The answer is, it’s not curved much.”
  • “One of the reasons we care is that a flat universe has implications for whether the universe is infinite,” says Schlegel.
  • … “That means – while we can’t say with certainty that it will never come to an end – it’s likely the universe extends forever in space and will go on forever in time. Our results are consistent with an infinite universe.”
  • … By 380,000 years after the big bang, however, the temperature of the expanding mixture had cooled enough for light to escape, suffusing the newly transparent universe with intense radiation, which in the 13.4 billion years since has continued to cool to today’s faint but pervasive cosmic microwave background.
  • … BOSS collaborator Beth Reid of Berkeley Lab translates the two-dimensional sky coordinates of galaxies, plus their redshifts, into 3-D maps of the density of galaxies in space. “It’s from fluctuations in the density of galaxies in the volume we’re looking at that we extract the BAO standard ruler,” she says.
  • …. The universe’s expansion history has been measured with unprecedented accuracy during the very stretch of ancient time, over six billion years in the past, when expansion had stopped slowing and acceleration began. …

At this point I gave up.

My knowledge of physics and astronomy is sadly lacking and I cannot be reconciled to a universe which is

  • an expanding universe, where
  • the expansion is accelerating, and where
  • the university is infinite, and
  • timeless, and 
  • has been “measured” to an accuracy of 1%

1% of an infinite universe ought to be infinity in my boggled mind!  Is the “ruler” expanding as well? And did time exist before the Big Bang? And if the universe is “timeless”, is time just an artificial construct? And can infinity expand without having a larger infinity?

Oh well! I’m afraid I cannot picture this universe – but I am only an engineer.

Lauren Anderson et al, The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: Baryon Acoustic Oscillations in the Data Release 10 and 11 galaxy samplesMonthly Notices of the Royal Astronomical Society, 2014.

Abstract: We present a one per cent measurement of the cosmic distance scale from the detections of the baryon acoustic oscillations in the clustering of galaxies from the Baryon Oscillation Spectroscopic Survey (BOSS), which is part of the Sloan Digital Sky Survey III (SDSS-III). Our results come from the Data Release 11 (DR11) sample, containing nearly one million galaxies and covering approximately 8500 square degrees and the redshift range 0.2the baryon acoustic oscillation (BAO) feature. The acoustic features are detected at a significance of over 7σ in both the correlation function and power spectrum. Fitting for the position of the acoustic features measures the distance relative to the sound horizon at the drag epoch, rd, which has a value of rd,fid=149.28Mpc in our fiducial cosmology. We find DV=(1264±25Mpc)(rd/rd,fid) at z=0.32 and DV=(2056±20Mpc)(rd/rd,fid) at z=0.57. At 1.0 per cent, this latter measure is the most precise distance constraint ever obtained from a galaxy survey. Separating the clustering along and transverse to the line-of-sight yields measurements at z=0.57 of DA=(1421±20Mpc)(rd/rd,fid) and H=(96.8±3.4km/s/Mpc)(rd,fid/rd). Our measurements of the distance scale are in good agreement with previous BAO measurements and with the predictions from cosmic microwave background data for a spatially flat cold dark matter model with a cosmological constant.

Another Sunday, another week — but why?

November 3, 2013

The seven-day week must go down as being one of the most “unnatural” yet persistent creations of man. It is very practical of course, but why do we have it?

There are no discernible periodicities that we have been able to find outside ourselves which take 7 days. There are no periodicities within ourselves either that are 7 days or multiples of 7 days.  There are no celestial or astronomical cycles in tune with 7 days. There are no movements of the sun or the moon or the stars that give rise to a 7-day period. There are no weather or climate phenomena that repeat with a 7-day period. There are no human behavioural patterns that dance to a 7-day tune. There are no living things that have a 7-day life cycle. (There is a branch of pseudoscience which claims that living cells may be associated with a weekly or a half-weekly cycle – a circaseptan or a circasemiseptan rythm – but this is still in the realms of fantasy).

It would seem logical that our ancestors must have first noted the daily cycle long before they were even recognisable as human.  As humans they probably then noted the lunar cycle of about 29 days and the yearly cycle of about 365 days. Our distant ancestors would also have noted that the period of the yearly cycle was a little more than 12 lunar cycles. By about 35,000 years ago we have evidence that the lunar cycle was known and was being tracked. This evidence is in the form of a tally stick with 29 marks – the Lebombo bone.

The development of beliefs in gods of light and separate gods of darkness is not so difficult to understand. The gods of winds and fires and mountains and rivers are equally understandable. The fact that the lunar cycle was rather badly synchronised with the annual solar cycle could well have led to the concept of sun-gods and moon-goddesses, each with their own areas of influence.  (In fact, considering the imperfection of the design of the universe which is manifested in the lack of synchronisation between the various celestial cycles, it is difficult to understand how a concept of a single all-powerful creator ever arose. Why would such a poor design be the product of an all-powerful creator? Surely he could have managed the simple 3-body problem to synchronise the various rotations of the earth, the moon and the Sun?)

The invention of the seven-day week can best be dated to be at least 5,000 years ago to the time of the Babylonians. It was certainly long before the Old Testament came to be written to fit with the 7-day week which had already been invented and established. The story goes that

the seven-day week was actually invented by the Assyrians, or by Sargon I (King of Akkad at around 2350 B.C.), passed on to the Babylonians, who then passed it on to the Jews during their captivity in Babylon around 600 B.C.  The ancient Romans used the eight-day week, but after the adoption of the Julian calendar in the time of Agustus, the seven-day week came into use in the Roman world. For a while, both the seven and eight day weeks coexisted in the Roman world, but by the time Constantine decided to Christianize the Roman world (around A.D. 321) the eight-day weekly cycle had fallen out of use in favor of the more popular seven-day week.

The idea that the 7-days originates from a division of the lunar cycle into 4 seems improbable. The lunar cycle (synodic period) is 29.5305882 days long. Three weeks of 10 days each or five 6 day weeks would fit better. That the annual cycle of 365.2425 days comes to dominate is not so surprising. Our calendar months are now attuned to the annual cycle and have no direct connection to the lunar cycle. But it is our 7 – day weeks which remain fixed. We adjust the length of our months and have exactly 365 days for each of our  normal years. We then add an extra day every 4 years  but omit 3 such extra days in every 400 years to cover the error. We make our adjustments by adding a day to the month of February for the identified leap years but we do not mess with the 7 days of the week.

It is far more likely that the 7 days comes from the seven celestial objects visible to the naked eye from earth and probably known to man some 5,000 to 10,000 years ago. They were familiar with the Sun, the Moon, Mars, Mercury, Jupiter, Venus, and Saturn by then. Naturally each was a god in his own heaven and had to have a day dedicated just to him/her/it. The same 7 celestial objects are used for the days of the week not only in the Greek/Roman Western tradition, but also in Indian astrology. The Chinese /East Asian tradition uses the Sun, Moon, Fire, Water, Wood, Gold and Earth to name the seven days of the week. But this must have come after the 7 day week had already been established elsewhere. (For example, to name up to 10 days they could just have chosen to add days named for the Air, Beasts, Birds ….). Some languages use a numbering system and some use a mixture of all of the above. Rationalists and philosophers and dreamers have tried to shift to 5 and 6, and 8 and 10 day weeks but none of these efforts has managed to challenge the practicality or to dislodge the dominance of the seven-day week.

And now the whole world lives and marches – socially, culturally, politically – to the inexorable beat of the 7-day week.

Just because some long-forgotten astrologer/astronomer decided that he would dedicate each day to one of his seven known celestial gods (and he only had seven)! Even if he (unlikely to have been a “she”) worshipped an Earth-goddess, she must have been considered inferior to the celestial gods. Otherwise we would have had an 8-day week! 

An alien race could be excused for concluding that humans must have evolved from once having seven fingers on each limb. Or that we once had seven limbs and have lost 3. Or that humans have an innate circaseptan rythm requiring extra rest and sleep every 7 days. Or that humans have a physiological need to go binge drinking on the sixth day and need the seventh day to recover!

But if the 7-day week is a Divine creation then the aliens will also have a 7-day week and will not be in the least surprised.

The number seven does have a few special properties:

Not forgetting the Seven Wonders of the Ancient World. But they only came after the seven day week had been invented and introduced.

 


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