102mter 1 blllion light-years 十亿光年 Most of space looks as cmpty as this,the glow of distant galaxies like douted dust.This emptiness is normal;our own bright home-world is the exception.A tenfold larger view would show no new structure,no new void;the universe is roughly uniform at such di. mensions.Novelty on so grand a scale is to be sought over time rather than from place to place.All swift change is in the past.This view will dim slowly,for a few billion years at east,as the faint dlusters drift still farther apart. m▣P.▣m
十亿光年
1024 eters ~100 million light-years 亿光年 We look toward our distant home in the Milky Way.But we sec mostly one large intervening cluster of galaxics,called the Virgo Cluster.Galaxies as a rule associate into orbiting dusters and groups.There is reason to believe that our Milky Way is itself an ouclier of the big Virgo Cluster,responsive to its steady gravicational pull:part of a supercluster.Out there beyond the Milky Way is a good-sized volume nearly devoid of noticeable galaxies. mgP.C▣m
一 亿 光 年
102moters ~10 million light-years~3 megaparsecs 一千万光年 These are the galaxies of our own cosmic region,cach single bright spot made by the summed light of stars by the billion.Their mutual gravity binds stars into galaxies,every one a complex swarm of moving stars. moP.C▣m
一 千 万 光 年
10mtr 1 million light-years 一百万光年 This fat circular disk is our own Galaxy,the Milky Way,with its spiral structure.It travels in space with two satellite galaxies,the irregular little Clouds of Magellan.Not many galaxies are larger than ours;nor are many seen that are smaller than the Clouds. moP.C▣m
一 百 万 光 年
100 thousand light-years 十万光年 We look face-on direcdly at the Milky Way spiral.A hundred billion stars murually bound by gravity encircle the central region,some passing close in,some in wider orbits.Our own sun swings with the rest in dignified passage clockwise about the distant galactic center,once every three hundred million years.External galaxies akin to our own are scat. tered throughout space as far as we can see.They too rotate slowly as they drift. m▣P.C▣m
十万光年
102mter ~10 thousand light-years 一万光年 Clouds of stars and glowing gas,with patches of darkening dust,mark the slow-changing spiral patterns of the Galaxy disk.Our distant sun cannot be seen here,but it is in the center of the image,near the border of one spiral arm. maP.C▣m
一 万 光 年
101 ~1 thousand light-years 一千光年 In this view we are within the disk of the Galaxy,right among a host of stars visible here as individuals.Almost every star of the thousand mapped by the old watchers of the sky. those who first gathered scars into constellations,lies within this square,our own galactic neighborhood.There are many other stars as well,too faint for the eye to see. maP.C▣m
一 千 光 年
71018 aters ≈100 light-years 一百光年 A skyful of distinct stars:One among them,central,but too faint to pick out,is our sun. The star Arcturus,prominent in the northern sky of earth,shines brightly.Arcturus is in- trinsically more luminous than our sun,and here we are nearer to it as well. m▣P,C▣m
一 百 光 年