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Journey Into The Universe

PKS 2126-I58 PKS 0231-23 3C 446 PHL S200 Q 0347-383 *aC 4543 PKS 2000-33o 'a 0420-388 A2645 OH 47 A 645 : ЗС 345 3C 295 oso o9s7-AR PG 247-26 6. KNOWN UNIVERSE e nhatevas direction we look inte deep space, we can detect clusters of galaxies and superclusters, all moving away from us. Toward the observable horizon, we see quasars-quasi-stellar objects-and the uniform glow of radiation from the big bang There is no center: any observer anywhere would see this same effect. The universe is isotropic; that is, it looks the same in every direction. Quasars, the most distant objects yet observed, are ameng the most curieus and the most energetic. Each of the brightest quasun enita the energy JOURNEY INTO THE UNIVERSE THROUGH TIME AND SPACE 5. LOCAL SUPERCLUSTER "My suspicion is that the universe is not only queerer than we suppose, but queerer than we can suppose." J.B.S. HALDANE Clusters of galaxies-lke fleets of ships-congregate in superclusters, the largest of celestial formations. Virgo, the closest rich cluster to our Local Group, is some S0 million light-years away, near the center of our lacal THEN PRIMITIVE MAN gazed at the void of heaven, his eye I at most a few thousand stars-a serene and ed universe. But now, far beyond the range of feeble sight, out on the limitless curve of space and time, science has revealed a universe of unimaginable size and inconceivable violence. Billions upon billions of stars- like our sun-burn with the energy of a thermonuclear furnace. Many die in explosions that litter the reaches of space with gas and dust from which new stars and planets probably the vilalent puc th distant galaxy. The farthest quasars are rushing away from us at more than 90 percent the speed of light. Their light traveled billions of years to reach us. During that time they evolved, and what they are ike today we have no way of knowing. To leek at such objects is to see the universe as it was bilions of years ago. W. se it has thousands of m Eaciting new pbservations of superclusters have shown enormous volumes of relatively empty space, or voids, between superclusters. Some cosmelogists speculate that the universe resembles a sponge in which the superclusters are interconnected, resembling thin filaments stretching between giant voids. Astronomers caleulate the masses of rich clusters as one way to estimate the density of matter in the universe. IH that density is at er below a critical umber, matter wy art forever in Yab on initiated by the big bang braking will slow the motion until the nlverse falls back together. are born. And from the vastness beyond the congregations of murmur, in microwaves, of the most cataclysmie event of all-the big bang of creation. When time began - perhaps as long as twenty billion years ago- all mass and energy were compressed almost to infinite density and heated to trillions upon trillions of degrees. A cosmic explosion rent that featureless mass, creating a rapidly expanding fireball. It has been cooling and slowing ever At first the universe was an impenetrable haze. During the first million years, temperatures dropped to 3000 kelvins (3000 degrees above absolute zero). Nuclei captured electrons, producing atoms that formed an unsettled gas of hydrogen and some helium. The universe cleared and everywhere blazed with light. Denser regions of gas, pulled together by their own gravity, resolved into stars collected in aggregations called galaxies. Today's universe continues to expand. The early radiation, cooled by the expansion to 3K, can be detected in every direction by radio telescopes - the remnant echo of the big bang. But what ca Billions of years hence, will gravity overcome the all matter back into its primordial state - in a big crunch? And if the universe is closed, might another big bang follow, with another expansion? Or, as many astronomers now believe, will an ever expanding, or open, universe end in a whimper, its galaxies scattered irretrievably, their star fires spent and cold? For now, the questions are the domain of the philosopher as well as the astronomer. of slars comes th * perlaters * Chatersof Galales + Guasar Sculptor Ginden tregh , wth rid meed in ight- a show inreingly gelme of yee1 ndi hep caloulate the ditance of celeste objecta pmiected on a at dwaadiaf 20 blon Eight-pears NGC 3923 Lettern and uen refer to catalog lig eh A IS14 in the i catalog of rich clater Mstands for Messier, and NGC New Gener Catalgu a Caters of Galie • Singe Geleies NGC 3672 NGC 2964 before the big ad how will ion and pull came bang, and all end? NGC 2207 2. SUN'S NEIGHBORS The sun is in universal terms an ordinary yellow star, shown here with its 20 closest neighbors. Distances are given in light-years-how far light travels in one year at almost 300,o00 kilometers (106 000 miles) a second. Sunlight, for instance, takes a full minutes te cress the I50 Hilla kn to ur ere reaching the planet Pluto. After about 4 years 4 montha it touches Alpha Centauri, our nearest stellar neighbor, 43 light-years, or Predaced by the Cartographic Divisiee National Geographic Soclety GILMATM GROVENOR PNDENT NATIONAL GEOGRAPHIC MAGAZINE WILURE GARRATT, DITOR 3LKY WAY GALAXY O thought to be the ve until discoveries in the day we know it is only one of lies. It is a gravitationally ating congregation of Silons of stars. The ews with the light of ars Globular clusters oldest stars- a lS billion vears. Gas a i in the spiral arma a ng new stars. ln one oy Mthe galary center e New ye, travelis Cam Cer Can ly ge Andrameda Galany, MaNGC 20s Giobular Clusters M "NGC 147 And A And Alpha Centauri is actually a multiple system with three stars locked by gravity in orbit around each other Indeed many stars are binary or multiple. Single stars, though, seem more likely to have planetary systems like our own. The Space Telescope to be orbited soon would detect any Jupiter size planet associated with Barnard's star, almost 6 light-years away. 4. LOCAL GROUP Beyand the Milky Way we have located galaxies in every direction. Our own is part of a loosely bound cluster of some 20 galasies, called prosaically the Local Group. Galaies are to astronomy what atoms are te physies astronomer Allan Sandage has said, and this greup illustrates the variations he Miky Way, its sister Andromeda IMS, and themaler Ma3 re TAat- ny clede lie mitNin the Andromeda galary, Itself ance EN mistakenly derntified asa nebula, on cloud, in the Milky Way galary. NGC 205 is an elliptical galary, consisting mainly of old stars. The Large and Small Magellanie Clouds are iregular galasies, described as haze in sand da esean matter Ursa M R Grebrdge 34 e Miky Way Leiende 2s SculptoreSnati Magelianie Cleud Large Magelanie Cloud NGC G822 1. SUN AND NEAR PLANETS A vast elgud ofS And dust collapses some 46 bllian vear Me. Compression spawns a Har in the hub of the rotating disk-shaped , and ou sun's thermonuelear furmace s up. Varloua materials condense from the ing disk, collide, and coalesce to form the ta and other features of our solar atem. The three terrestrial, or earthlike Peta shown here are solid spheres with b tores. Earth and Venus possess Whenres, but only earth's sstalns life. hede iddle-aped sun exhausts ite Merc u, it will expand, devouring Aemi venus and turning the earth into APPARENT MAGNITUDE the sutharn sh y Magellan'sErEN in 1520. Thase member galaies all moving in random patha, are held together by gravity, even as the universe expands. erew Te Ceti -24 te Alpha Centa ith 20(nlesee Coinftindunmermpertn trom ed t te he het COPGHT ENATONAL GEOGRAPHC SOCETY, WANCTON DC inferno.

Journey Into The Universe

shared by kcatoto on Jan 17
When primitive man gazed at the void of heaven, his eyes discerned at most a few thousand stars - a serene and limited universe. But now, far beyond the range of feeble sight, out of the limitless cur...


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