“And God Said, Let There Be Lights in the Firmament of Heaven”

BYU Studies Quarterly BYU Studies Quarterly

Volume 30 Issue 4 Article 5

10-1-1990

“And God Said, Let There Be Lights in the Firmament of Heaven” “And God Said, Let There Be Lights in the Firmament of Heaven”

R. Grant Athay

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Recommended Citation Recommended Citation Athay, R. Grant (1990) "“And God Said, Let There Be Lights in the Firmament of Heaven”," BYU Studies Quarterly: Vol. 30 : Iss. 4 , Article 5. Available at: https://scholarsarchive.byu.edu/byusq/vol30/iss4/5

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and god said let there be lightsin the firmament of the heavenheaven9595

R grant athay

OUR MAJESTIC SUN

it is new years morning the sun has not yet risen at ourwinter home in the sonoran desert of arizona the air is clear andcold and I1 eagerly await the warmth of the morning sun As I1 waitI1 resolve to share my knowledge of the sun that marvelous sourceof light and energy introduced by the simple words and god saidlet there be lights in the firmament of the heaven to divide the dayfrom the night and let them be for signs and for seasons and fordays and years and let them be for lights in the firmament of theheaven to give light upon the earth and it was so while conveyingthe message that god is the creator of heaven and earth this briefpoetic account makes no attempt to emphasize the enormity andgrandeur of that creation

the suns enormity and grandeur are of great interest to mesolar research has been the central focus of my career as anastrophysicist beginning some forty years ago at an observatorylocated in the high mountains of colorado where I1 daily focused acarefully designed and precisely crafted telescope on the rising sunmy pursuit of the sun has taken many turns it has taken me to othermountain observatories in new mexico arizona california ha-waii the high pyreneesPyrenees and the swiss german and japanese alpsat other extremes it has taken me to the deserts of africa and toremote islands in the atlantic and pacific oceans recently theseobservation sites have been supplemented by powerful extraterresextraterrestrial observatories placed in orbit by rockets or carried aboard thespace shuttle in using the unique data collected from these remoteobservatories I1 have worked with the worlds most powerfulcomputers as well as the most recent scientific theories hundredsof colleagues in the US and in foreign lands have shared and aidedin these efforts some of my colleagues have flown as astronauts

R grant athay is an astrophysicist at the national center for atmospheric research in boulder colorado

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Athay: “And God Said, Let There Be Lights in the Firmament of Heaven”

Published by BYU ScholarsArchive, 1990

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and others have endured the intense cold on the high plains ofantarctica in order to carry out delicate observations of the sunwithout interruption night and day for several days still others havebuilt large facilities in deep mine caverns for detecting neutrinosthe most elusive of all solar radiations emitted from the very coreof the sun and able to travel almost unimpeded through both the sunand the earth

hardly a day has gone by during these past forty years that I1have not puzzled over the unsolved mysteries of the sun whilewaiting for the sunrise and reflecting over the past years I1 am stillfilled with awe by the beauty and majesty of this heavenly objectI1 am awed that this star of dwarfish proportions compared to otherstars so effectively delivers light and heat to a small planet ninetythree million miles away I1 am awed by the complexities associatedwith that delivery the energy in the suns rays that I1 will soon enjoystarted its journey several million years ago from the extremely hotdense core of the sun at that time the energy was mainly in the formof x rays gradually diffusing toward the suns surface in theiroutward diffusion the x rays gradually softened and by the timethey reached the surface they had been converted into the warmgentle rays of light and heat so familiar to us by current estimatesthis slow tortuous journey from the center of the sun took aboutfifteen million years yet scarcely more than eight minutes isrequired for the journey from the suns surface to the earth

we have learned a great deal about the sun and we continueto learn at an accelerated pace several volumes are required todocument and explain this knowledge yet much of what weobserve about the sun still defies comprehension and gives rise tosome sense of defeat many of the mysteries have only growndeeper and more baffling as we have learned more about them inmost respects the sun remains our teacher and we are subdued bythe knowledge that none of us fully comprehends the suns com-plexityplexity nevertheless in trying to understand the sun we havelearned much about the universe in which we live

the sun is one of our most valuable laboratories for studyingthe basic physical processes of the universe as well as those of ourown world the sun displays a panorama ofphenomena that cannotbe duplicated on earth on special days it is violently active and onother days relatively calm even at its calmest moments howeverit is restless and seething by unraveling its mysteries we enhanceour knowledge of our environment

it is a tribute to modem man that we have learned so muchabout the universe most of what we now know has been learned inthe technological boom of the last few decades centuries of earlier

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BYU Studies Quarterly, Vol. 30, Iss. 4 [1990], Art. 5


let there be lights 41

work was limited by a lack of knowledge of atomic and nuclearphysics and of the basic laws of thermodynamics on the planetearth we live in a protected subdued environment in interpretingthe universe around us we have been forced to open our minds tocircumstances far beyond anything we have experienced in addi-tiontion we have had to use every tool of modem science and technoltechnow

ogyagy and to invent new tools when the need arose thus when weconsider the achievement and potential of modem astronomy wehave much to be proud of pride for these achievements turns tohumility however when we realize what prophets of old learnedwithout the benefits of modemmodern science and technology throughfaith in god and a desire to understand his creations they advancedtheir knowledge of the universe far beyond the secular knowledgeof their day

consider the following verses from the vision of moses andworlds without number have I1 created for behold there are manyworlds thathave passed away and there are many that now standand innumerable are they unto man the heavens they are manyand they cannot be numbered unto man and as one earth shallpass away and the heavens thereof even so shall another come andthere is no end to my works moses 133 35 37 38 to interpretthe meaning in these phrases we must first define earths worldsand heavens A common definition of worlds refers to human ac-tivitiestivities together with their environment similarly in the book ofmoses the term earths appears to refer to planets occupied byhumans this usage is consistent with the primary theme of thebook of moses which is mans relationship to god for beholdthis is my work and my glory to bring to pass the immortality andeternal life of man moses 139 thus we shall define worlds andearths as being synonymous the term heavens clearly refers to thestars star systems and other objects in those portions of theuniverse in proximity to an earth or world for those of us on earthheavens refers mainly to our own galaxy and more specifically tothe stars and planets in our own neighborhood of the galaxy lastlywe shall interpret passing away as a form of death or at leastchanges of such proportions that a previous state ceases to exist

with these definitions the phrases quoted from moses stateseveral important facts planets and stars have finite lifetimes theyarebornarnebornare bormbornbomm and they die many have already died and new ones havereplaced them creation therefore is an ongoing process our earthand sun were not the first planet and star they had ancestors andwhen they die they will have offspring in the scenario revealed tomoses humankindshumankinds temporary occupancy of earth represents buta single family living in one generation of a family tree consisting

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of innumerable other civilizations on other earths which have theirown stars and heavens earlier generations have passed away andnew ones have yet to emerge

moses portrayal of a living evolving universe in which allthings have rhythmic life cycles is in perfect harmony with modemastronomy and astrophysics what moses learned through revela-tion we have had to leamlearn through observations and the gradualdiscovery of the physical laws that describe the behavior of matterin the universe an effort that has involved thousands of scientistsand engineers

OASES IN THE UNIVERSE

during the early nineteenth century the scientific world be-lieved that the sun the moon and all the planets of the solar systemwere inhabited little was known about the nature of stars or thepossibility of other planetary systems resembling our own al-though the universe was looked upon as friendly and nourishing tolife we have since learned that life as we experience it couldsurvive without external support in relatively few places in theuniverse other planets in the solar system either lack air and wateror they have noxious atmospheres and impossibly severe climatesthe sun is gaseous throughout with no solid surfaces and is far toohot for earth life to exist thus in this solar system the planet earthis unique as an abode for man

when we look among other stars for possible earths we findthat most are unsuitable for another earth we would need a singlestar to provide heat and light as well as a constant gravitational fieldin which to orbit most stars occur in clusters ranging from pairsto swarms numbering tens of thousands none of these is a goodcandidate in the complex and constantly varying gravitational envi-ronment of star clusters there are no stable orbits where planets cansurvive for long periods of time by orbiting a single star neverthe-less among the twenty billion stars of our galaxy we still expect tofind millions of possibilities for earthlikeearth like planets sprinkledthroughout the galaxy and separated from each other by an averagedistance of several tens of light years

even when we find isolated stars with steady gravitationalfields conditions are notnecessarily suitedforlifesuited for lifeilfe we are accustomedto thinking ofour suns steadiness and dependability and its beneficialsupply ofheat and light however the sun is also unsteady undependdependunable and hostile to life in fact we survive in the solar system onlybecause earth acts as an oasis which protects us from the lethalradiation that appears to be a natural property of most stars

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for reasons not fully understood the sun reaches a minimumtemperature just outside its visual surface from that minimum ofabout 4500 degrees centigrade the temperature of the gas aroundthe sun climbs rapidly to a million plus degrees centigrade this hotgas surrounds the sun in a tenuous corona which influences theentire solar system the corona emits x rays faintly at times andbrilliantly at others it also emits energetic particles that like sub-atomic bullets spray the earth and other planets like the x raysthese particles are sometimes weak and sometimes intense but arealways deadly to life

most of these particles are stopped in the earths upper atmo-sphere very few reach the surface and fewer hit a human beinghowever each particle that enters our bodies may kill cells in ourtissues and organs and convert some to cancerous cells our bodiescan tolerate some particle bombardment but they cannot toleratelarge uncontrolled doses As the radiation dosage increases therate at which cells die or become cancerous increases leading ifsafe limits are exceeded to radiation sickness and death

solar particle radiation is highly sporadic and at times exceedssafe limits to anyone exposed to its full intensity it is a concern forastronauts and for aircraft crews flying high altitude polar routeswhere exposure to solar particle radiation is much enhanced

since our first penetration of space in the 1950s by rocketssalvaged from world war 11II we have flown xrayx ray cameras andparticle detectors beyond the earths protective shield we nowhave firsthand knowledge of these lethal solar radiations and theirvariations the x rays and particles from the sun rise and fall inintensity with the sunspot cycle which lasts roughly eleven yearssuperimposed on this cyclic variation are short lived flares of moreintense radiation occurring most frequently near the peak of thesunspot cycle from earth we see the effects of the x rays andparticles as unusual displays of the northern lights storms in theearths magnetic field and disruptions to shortwaveshortwave radio commu-nications all these phenomena originate high above us in theearths outer atmosphere

exactly why the sun has an active hot corona and how itaccelerates energetic particles remains a mystery however the sunis not unique in this respect xrayX ray cameras in space reveal that moststars have a hot corona surrounding them earth based observato-ries detect cycles of activity on even very distant stars these stellaractivity cycles are similar in character to those of the sun even tothe occurrence of starspotsstarspots and short lived flares of more intenseradiation therefore these stars probably produce energetic par-ticles in addition to the x rays that we observe indeed these stars

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may produce many of the mysterious cosmic rays that continuouslybombard the earthjustearth just as energetic particles from our sun stream outbeyond the solar system to bombard other stars and their planets

although we do not understand the specifics of the processesby which stars produce hot coronas and accelerate energetic par-ticles we have identified the essential ingredients of these pro-cesses those ingredients are ions rotation and internal motion allstars possess the first two and most possess the third all stars arehot enough to free electrons from the more easily ionized elementssuch as iron and other metals some rotate slowly others rapidlybut all rotate A majority as is the sun are stirred by restless convec-tion in combination these three ingredients act as a giant dynamothat generates magnetic fields these magnetic fields in turn arepushed and carried about by the restless ionized gases of the starthis buffeting of the magnetic fields provides the means for heatingstellar coronas and accelerating electrically charged particles to highenergies the high temperature of the sun ionizes solar elements andsupplies abundant free electrons and positive ions thus stellaractivity cycles with their x rays and energetic particles are a naturalconsequence of the most basic properties of stars the cycles ofactivity consist ofdynamo cycles in which magnetic fields are gene-rated and decay the magnetic fields are a form of energy and someof this energy reappears as the energy of the corona both on the sunand on other stars starspotsstarspots are at the loci of unusually strongmagnetic field concentrations and it is over these starspotsstarspots that thecoronas shine brightest and are the most active

in our universe stars provide the energy essential to life but atthe same time produce harsh radiation that destroys life our sun is

no exception just as a desert oasis provides water along with foliagewhich protects one from the heat of the midday sun the earthprovides necessary nutrients along with a protective atmosphereand magnetic field without which none of us could survive againwe recognize that just as the ingredients of life are natural to the sunand earth the harmful radiations are equally natural life in theuniverse is precarious and for life to exist elsewhere would requireplanetary oases similar to earth orbiting isolated stars of modest orweak coronal activity

along with the discovery that our sun has an unfriendly sidecaused by its corona we are learning much about the suns interior

BENEATH THE SUNS SURFACE

compared to the earth the sun is a giant its diameter of 870000miles is over 100 times that ofearth and its mass exceeds the earths

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by 330000 times however our sun belongs to a populous class ofsomewhat dwarfish stars some supergiant stars are a hundred timesmore massive some nearly a thousand times larger in diameter andsome a hundred thousand times more luminous at another ex-treme there are stars much smaller in diameter than the earth butmore massive than the sun

stars produce prodigious amounts of energy energy flowsthrough the solar surface at the approximate rate of 8000 horsepower per square foot even as far away as the earth the energy insunlight is over 1.51515 horsepower per square yard in more graphictentermsns the sunlight falling on a full size horse standing in a sunnyfield at midday carries more power than two horses working at anormal rate

attempts to explain such vast amounts of energy ended infrustration until the first half of this century when albert einsteindiscovered a formal equivalence between energy and mass othersprobed the nuclei of atoms and experimented with nuclear reactionsuntil it became clear that nuclear energy provided a promisingexplanation for the suns power other possibilities had beenconsidered earlier including energetic chemical reactions such asexplosives and the power of the suns gravitational energy thesemore conventional sources can produce sufficient energy for shortperiods of time but they have limited reserves the shrinking sizeof a star under the force of gravity does provide the main source ofenergy during the fonformativenative youthful stages of stars but cannotsupply enough energy for stars the age of the sun nuclear energyon the other hand is enormously more efficient and easily providessufficient fuel to power the sun for several billion years furthermore the hot dense interior of the sun provides just the properenvironment to stimulate and nourish thenuclearthe nuclear reactions

the chemical makeup of the sun and stars is determined bya spectral analysis of the light those stars emit each atom andmolecule regardless of whether it is in the laboratory or in a distantstar leaves its own unmistakable fingerprint in the light spectrumthroughout the universe stars are composed mainly of hydrogenwith only traces of heavier elements the next most abundant ele-ment is helium followed by oxygen nitrogen and carbon metalatoms are less abundant still in the sun 90 percent of the sunsatoms are hydrogen about 10 percent are helium and all otherscombined make up less than 00.10101oi 1 percent the most common nuclearreaction in the sun is the fusion of hydrogen to create helium thesame process used in hydrogen bombs in this process about 0.70707

percent of the mass in the hydrogen nuclei is converted into energyin accordance with einsteinsernsteinsEinsteins famous equation the remaining 99.3993

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percent forms the mass of helium nuclei even though only a smallfraction of the hydrogen mass is converted to energy this reactionalone can sustain the sun for a billion years at its present level ofpower by fusing only about one percent of the available hydrogeninto helium in reality even less consumption of hydrogen isrequired because ofother nuclear reactions that occur along with thehydrogen helium reaction we expect the sun to use up much morethan one percent of its available fuel during its lifespanlife span thus thesun should continue in its present state for several billion years

once we know the source of the suns energy and its massradius luminosity and chemical composition we can determine itsinternal structure for the sun to remain in equilibrium the energyproduced by its internal nuclear reactions must equal the observedluminosity and must be carried to the surface at exactly the same ratethat it is generated also the pressure inside the sun must be highenough to support the weight of the overlying material thesefactors the rate ofenergy production the rate of energy flow to thesurface and the pressure are regulated by the temperature anddensity inside the sun therefore the equilibrium requirements onthe pressure and energy generation together with the observed sizechemical composition mass and luminosity enable us to determinethe internal temperatures and densities

at the center of our sun the temperature rises to 20 milliondegrees centigrade 45 million degrees fahrenheit and the pres-sure rises to three billion tons per square inch the enormouspressure compresses matter to a density about ten times that of solidlead even though it is made up mostly of hydrogen the lightest ofall elements because of the high temperature however even thisvery dense material is still a gas each atom is free to race about athigh speed among its very crowded neighbors As a whole the solargas in the deep interior is still and moves only with the solar rotation

higher temperatures and densities accelerate nuclear reac-tions As a result most of the energy that escapes the solar surfaceis generated near the very center of the sun during most of itsjourney to the surface the energy diffuses slowly outwards in theform of radiation but the hot solar gases are extremely opaqueallowing photons of radiation to travel only short distances beforebeing absorbed and then reemitted the reemission occurs inrandom directions causing the photons to travel backwards nearlyas often as forwards thus progress to the surface proceeds slowly

for about the last quarter of the distance from the suns centerto the surface the gas becomes restless A broad zone of convectionsets in with hot ascending columns separated by cool descendingplumes this convection gives rise to a net upward flow of heat that

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is much more efficient than the slow diffusion of radiation therebydecreasing the time required for the energy to reach the surfacenonetheless the journey from the suns center to the surface requiresapproximately 15 million years

even though we can model the interior structure of the sun tosuccessfully produce its observed bulk properties we continue toseek new means for testing the model two very different tests arecurrently in use one involves elusive particles known as neutrinosthat occur as productsbyproductsby of the nuclear reactions A second involvessound waves generated by the turbulent action of the convection zone

As their name implies neutrinos are electrically neutral theyhave little or no mass at most a tiny fraction of the electron massthey interact only slightly with the more common forms of matterand almost all of them escape the sun without difficulty for thesame reason however they are very difficult to detect and not agreat deal is known about their properties but we do know the rateat which nuclear reactions are occurring in our solar model and asa result we can predict the rate of neutrino production by measur-ing the neutrino flux we have a direct test of the interior model

the task of measuring solar neutrinos has been undertaken byphysicists working thousands of feet underground in deep minesby placing the neutrino detector in underground mines they hopeto shield the detector from other forms and sources of radiation thatcould influence neutrino detection their equipment includes largetanks containing thousands of tons of fluid in which a few neutrinosare detected each year the neutrinos themselves are not detecteddirectly but in passing through the detector they produce intricatebut detectable changes in the fluid the rate at which these changesoccur provides a measure of the neutrino flux

different nuclear reactions produce different species of neu-trinos but there is evidence that neutrinos can evolve into a differentspecies in less time than it takes them to travel from sun to earthneutrino detectors generally detect only one type of neutrino soobservations need to be made with several different detectorsalthough only one species of solar neutrino has been studied thusfar the results have created much excitement the observed neu-trino flux is less than half the amount predicted either the solarmodel is not quite correct or most of the neutrinos of the typedetected have evolved into a different species and in so doing haveescaped detection we will not know the answer until we have a setofobservations which includes the other species ofneutrinos whenthe answer does come we will learn more about the solar interior ormore about the fundamental nature of neutrinos themselves

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whichever way the answer to the neutrino riddle turns out weprobably will not need to radically revise the interior model of thesun the types ofnuclear reactions that occur in the sun are extremelysensitive to temperature so relatively small changes in temperaturecan substantially alter the flux of particular species of neutrinosalso other factors not accounted for in the models can alter therates of particular reactions and their associated rates of neutrinoproduction As we fine tune the model to agree with the measuredneutrino fluxes we may need to account for some of these second-ary influences until we finally solve the neutrino problem how-ever we will continue to be uneasy about just what goes on insidethe sun

the second means of studying the solar interior involvestechniques similar to those used in terrestrial seismology the con-vection of the gases and the intense flow of radiation in the sunproduce a variety of wave modes including sound and gravity wavesgravity waves propagate mainly horizontally but sound wavestravel in all directions those that go upward are reflected back bythe hot solar atmosphere As the reflected waves travel downwardthe increasing density and temperature in the interior of the suncause the waves to follow a curved paththatpath that eventually leads themback to the surface where they are again reflected by the hot atmo-sphere above thus the sound waves are trapped within the outermantle of the sun the higher frequency waves are trapped in thelayers nearest the surface while the lower ones penetrate deep intothe interior As in an organ pipe the trapped waves resonate atcertain well defined frequencies determined by the size of theenclosure and the speed of sound the sun resonates especially towaves with periods about five minutes long hundreds of suchresonances occur with measurable amplitudes that reveal the peri-odic fluctuations of the solar surface in both brightness and velocity

precise measurements of the frequencies at which the sunresonates provide information about how both the speed of soundand the rate ofrotation vary with depth temperature determines thespeed of sound so measuring sound provides a measure of theinterior temperature temperature measurements in turn serve asa check on the solar model studies of internal rotation are importantfor understanding such phenomena as the sunsuns9 s dynamo action andthe rate at which one layer mixes with another rotation studies arebased on the fact that the rotation of the sun splits each resonancefrequency into two closely spaced components whose separation isproportional to the speed of the rotating gas

precise measurement of the suns resonance frequencies re-quires observations over long periods of time with as little interrupinterrupt

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tion as possible the days of midnight sun in summertime at theearthsearth s poles have been used with moderate successsucces s but improvementsare needed solar physicists are currently building a network of sixobserving stations located at strategic longitudes around the globeand at sites noted for their sparse cloudiness identical instrumentsplaced at each site will provide observations interrupted only byoccasional periods of simultaneous cloudy weather at consecutivesites also a joint US and european satellite currently in anadvanced planning stage will carry an instrument for measuringsolar oscillation frequencies the orbit will be such that the satellitewill experience the long periods of uninterrupted sunlight ideal forthe accurate measurement of frequencies

by such techniques and perhaps others yet to be discoveredwe will gradually come to understand the primary structure andphenomena of even the deepest layers of the sun whatever happensin the interior of the sun will influence the surface layers in anobservable way therefore interpreting surface phenomena cor-rectly discloses events in the interior

THE generations OF THE STARS

the first step for understanding the universe is a reliable mea-surementsu of distances the standard unit of distance in astronomy isthe light year the distance light travels in one year through spaceone light year is approximately 6 trillion miles or 63000 times thedistance from sun to earth

the distances to stars inin our immediate neighborhood aremeasured by triangulation the method used by surveyors to mea-sure distances beyond the reach oftheir tapes As a baseline for thesemeasurements we astronomers use the diameter of the earths orbitwhich is 16.6166 light minutes by such measurements we discoverthat the star nearest the sun is more than 4 light years away and thatsome 100 stars inhabit space within 22 light years from earth themean distance between these 100 stars is 7.67676 light years

triangulation gives reliable distances for tens of thousands ofstars which is a large enough sample to establish some of the basicproperties of stars and determine how these properties are interreinterralated added evidence comes from studying compact clusters ofstars which reside at such great distances from earth that all the starsin the cluster are effectively at the same distance cluster studiesadded to those of the nearby stars show that there are close relation-ships between a stars spectrum of colors and the stars absolutebrightness absolute brightness depends on the stars total rate ofenergy radiation and this remains the same regardless of the stars

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distance from earth the apparent brightness of a star depends on itsabsolute brightness and its distance from us As the distanceincreases the apparent brightness decreases in a known waydoubling the distance decreases the apparent brightness to a quarterof its former value thus by carefully measuring astars spectrum wecan determine its absolute brightness and if we then measure its

apparent brightness we can determine its distance similarly thebrightness of some stars pulsates with periods ranging from frac-tions of days to weeks such stars exhibit a close relationshipbetween the period ofpulsation and absolute brightness by measur-ing the period of pulsation and apparent brightness we again havea reliable measure of a stars distance

these techniques plus others work equally well on stars indistant galaxies by using a combination of techniques we havelearned that our milky way galaxy is in the form of a giant diskmeasuring some 150000 light years in width and 50000 lightyears in thickness our solar system is located approximately27000 light years from the galactic center roughly 140000 lightyears from us are two other galaxies named the magellanic cloudswhich are visible to the naked eye from the southern hemisphereanother dozen galaxies are within 1.616lgig million light years of earthand complete a local cluster of galaxies beyond these are otherclusters many measuring in excess of 10 million light years inwidth and containing hundreds of galaxies on a still grander scalewe see in all directions galaxies and groups of galaxies arranged inpatterns extending as far as our best telescopes can see which isseveral billion light years

since distance can be expressed as light years distance is

equivalent to time A star located 50000 light years from us is seentoday as it was 50000 years ago and a distant galaxy a billion lightyears away is seen as it was a billion years ago we thereforecannot escape the conclusion that the age of our universe extendsbillions of years back in time

modem science was not the first to posit such an ancientbeginning for the universe the universes age was apparentlyknown to the prophet abraham A quotation taken from the timesand seasons states

eternity agreeably to the records found in the catacombscatacombs ofegypt hasbeen going on in this system not this world almost two thousandfivethousandfivehundred andfiftyfiveandany fifty five millions ofyearsofyears and to know at the same timethat deistsfeists geologists and others are trying to prove that matter musthave existed hundreds of thousands of years it almost tempts theflesh to fly to god and see and know as we are seen and known

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this quotation appeared in the same time period as joseph smithstranslation of the book of abraham which accounts for the refer-ence to records found in the catacombscatacombs of egypt in 1844astronomers werejustwerwere justejust beginning to realize the vastness ofour milkyway galaxy and what it implied in terms of ages they knew littleabout the universe beyond our galaxy similarly geologists werebecoming aware that the earth also had a much longer history thanthey had previously supposed not until this century however didscientists begin to think in terms of billions of years

what about our own star the sun how old is it how muchlonger will it last the answers to these questions come fromdiverse directions geologists set the age of the earth at approxi-mately 4.54545 billion years moon rocks gathered by astronauts androbotic lunar landings show the effects of exposure to solar particleradiation as it has accumulated over time the total amount ofdosage found in the moon rocks requires an exposure time of about4.54545 billion years at the current rate of solar particle radiation weknow that young stars are more active than old stars and we inferthat the sun radiated particles at a greater rate in its youth stellaryouth is measured in millions of years rather than in billions how-ever and even allowing for the increased activity of the youthfulsun the moon rocks still require a sun of the same age as the earth

we also learn about stellar ages from their evolutionary patternsthrough spectral classification we categorize young stars middleaged stars old stars and the remains of dead stars the sun is clearlyin the middle aged group it is a normal star albeit relatively in-active and somewhat dwarfish in size in the life ofa star middle agebegins after the formative phase of gravitational contraction hassubsided and the nuclear fire has been ignited in the stars core andmiddle age lasts an exceedingly long time there is little if anyreason for pronounced change as long as the nuclear fuel remainsplentiful As we noted in the preceding section the sun has suffi-cient fuel to bum steadily for several billion years

stellar death rates provide a measure of the average lifespanlife spanof stars we can determine death rates because some classes of starsbrighten spectacularly in their death throes and are readily identifiedeven in distant galaxies in a galaxy of 20 billion stars we expect tosee only a few stars die each year if the average star lives a fewbillion years on the other hand if the average life span were muchshorter many more stars would die each year by observing stellardeath rates we infer that stars of the same mass and absolutebrightness as the sun have a lifespanlife span of several billion years thusavailable evidence points to an expected lifespanlife span for our sun ofseveral billion years

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exactly where the sun is in its life cycle is not so readily deter-mined its level of activity suggests that the sun has been middle agedfor some time stellar aging is accompanied by a decreasing rate ofrotation or spindownspindown the sun is a slow rotator again suggesting arespectable age

what about our suns ancestry how many generations pre-ceded it not too surprisingly our galaxy is much older than the sunand approaches the age of the universe itself among star clusterswithin the galaxy we find both young and old the oldest grouphave ages of about 20 billion years star clusters in nearby galaxiesindicate ages similar to those in the milky way galaxy aside fromdetermining the ages of star clusters the primary means ofmeasur-ing the age of the universe is through its expansion rate galaxiesbeyond ours are moving away from us the more distant galaxiesare receding at a higher velocity than those that are nearer theexpansion velocities are so regular and so universal that they suggesta common beginning to the expansion itself the beginning of theexpansion is ascertained by projecting the observed law of expan-sion backward in time until the universe becomes compact this isthe so called hubble time currently evaluated at 17 billion yearswhich is compatible with the estimated ages of the older star clustersin our galaxy and in other nearby galaxies

both our galaxy and the universe are much older than the sunthus the sun was created in an already existing galaxy of stars it isof a relatively recent generation but not the most recent there isother evidence that our galaxy is a birthing center for stars withinthe galaxy there is much tenuous matter distributed between thestars additionally in regions of unusually dense interstellar cloudswe observe many very young stars most are in their youthful stagesof high activity and rapid rotation some appear to be just emerginginto an identity as a star numerous such birthing centers for starsare already known and with the new infrared technology of recentyears more are being discovered

each new generation of stars forms from the ashes of earliergenerations each generation consumes a little more of the plentifulsupply of hydrogen in the universe and in so doing creates morecarbon oxygen silicon calcium iron and all the elements withwhich we are familiar thus a stars chemistry reveals its historyand its ancestry early generation stars have only traces of heavyelements recent generations are much richer in the heavy elementsfused by earlier generations that have lived and died since the birthof the galaxy the suns chemical makeup suggests that it is of thefifth or sixth generation

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conclusiononce again an early morning hour finds me waiting for the

rising suns energy energy that has been traveling overovertheovertoethe previousmillions of years I1 wonder about earlier generations of stars whosedemise created the elements of the earth as well as those of the sunthe ashes of those same stars also supply the elements of which ourbodies and all living things on earth are made I1 am conscious thatthe warm gentle rays of the sun are vital to life while the deadly xrays and atomic bullets emanating from the suns fiery coronawould destroy life if we werent protected on our earthly oasis I1

marvel at all we have learned concerning the sun and the rest of theuniverse all referred to in genesis by the brief phrase and godsaid let there be lights in the firmament of the heaven but I1 yearnto know more much more

NOTE

times and seasons 5 1 january 1844 758

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Documents

“And God Said, Let There Be Lights in the Firmament of Heaven”