日ri全quan食shi是shi日ri食shi的de一yi種zhong，即ji從cong地di球qiu上shang的de部bu分fen地di區qu看kan到dao太tai陽yang被bei月yue球qiu全quan部bu遮zhe擋dang的de天tian文wen現xian象xiang。由you於yu月yue球qiu體ti積ji比bi地di球qiu小xiao，所suo以yi在zai月yue球qiu本ben影ying中zhong的de人ren們men才cai能neng看kan到dao日ri全quan食shi現xian象xiang。民min間jian稱cheng此ci現xian象xiang為wei“天狗食日”。日全食原理圖如下圖所示：

　　
　　2009年7月22ri

，chuxianleyicinandederiquanshi，zheshijinnianlaifashengderishizhong
，chixushijianzuichangdeyici。zhongguozuijiaguancequzaichangjiangliuyu，bizheyouxingzaihangzhoupaishedaoleruxiariquanshidezhuangmeijingse。

　　日全食期間，“食既”zhuangtaixia，suiranyueqiujiangtaiyangwanquanzheyanzhu，danyouyuyueqiubiaomianaotubuping，riguangrengketouguoaochufashechulai，xingchengleisizhenzhudemingliangguangdian，xiangduomudezhenzhugaogaodixuanguazaiqiheidetiankongzhong，chengwei“貝利珠”，因英國天文學家貝利首先觀測而得名。“貝利珠”出現的時間很短，通常隻有兩秒鍾，幸運的是
，筆者捕捉到了這一壯觀景色，圖：

 
　　
　　rishikeyiweiyanjiutaiyanghediqiudeguanxitigonglianghaodejihui。taiyanghediqiuyouzhejiweimiqiedeguanxi。dangtaiyangshangchanshengqiangliedehuodongshi，tasuofachudeyuanziwaixian、X射線、微粒輻射等都會增強，能使地球的磁場、電離層發生擾動，並產生一係列的地球物理效應，如磁暴、極光擾動、短(duan)波(bo)通(tong)訊(xun)中(zhong)斷(duan)等(deng)。在(zai)日(ri)全(quan)食(shi)時(shi)，由(you)於(yu)月(yue)球(qiu)逐(zhu)漸(jian)遮(zhe)掩(yan)日(ri)麵(mian)上(shang)的(de)各(ge)種(zhong)輻(fu)射(she)源(yuan)，從(cong)而(er)引(yin)起(qi)各(ge)種(zhong)地(di)球(qiu)物(wu)理(li)現(xian)象(xiang)發(fa)生(sheng)變(bian)化(hua)。因(yin)此(ci)通(tong)過(guo)日(ri)全(quan)食(shi)時(shi)進(jin)行(xing)各(ge)種(zhong)有(you)關(guan)的(de)地(di)球(qiu)物(wu)理(li)效(xiao)應(ying)的(de)觀(guan)測(ce)和(he)研(yan)究(jiu)具(ju)有(you)一(yi)定(ding)的(de)實(shi)際(ji)意(yi)義(yi)，並(bing)且(qie)已(yi)成(cheng)為(wei)日(ri)全(quan)食(shi)觀(guan)察(cha)研(yan)究(jiu)中(zhong)的(de)重(zhong)要(yao)內(nei)容(rong)之(zhi)一(yi)。
　　　
　　觀測和研究日全食
，還有助於研究有關天文、物(wu)理(li)方(fang)麵(mian)的(de)許(xu)多(duo)課(ke)題(ti)，科(ke)學(xue)史(shi)上(shang)有(you)許(xu)多(duo)重(zhong)大(da)的(de)天(tian)文(wen)學(xue)和(he)物(wu)理(li)學(xue)發(fa)現(xian)是(shi)利(li)用(yong)日(ri)全(quan)食(shi)的(de)機(ji)會(hui)做(zuo)出(chu)的(de)，而(er)且(qie)隻(zhi)有(you)通(tong)過(guo)這(zhe)種(zhong)機(ji)會(hui)才(cai)能(neng)獲(huo)取(qu)。最(zui)著(zhu)名(ming)的(de)例(li)子(zi)是(shi)1919年的一次日全食，證實了愛因斯坦廣義相對論的正確性。愛因斯坦1915年發表了在當時看來是極其難懂
、yejiqinanyizhixindeguangyixiangduilun，zhezhonglilunyuyanguangxianzaijudadeyinlichangzhonghuiguaiwan。renleinengjiechudaodezuiqiangdeyinlichangjiushitaiyang

，keshitaiyangbenshenfachuhenqiangdeguang，yuanchudeweiruoxingguangzaijingguotaiyangfujinshishibushiguaiwanle
，genbenkanbuchulai。danruguofashengriquanshi，dangzhutaiyangguang，jiukeyiceliangchulaiguangxianguaimeiguaiwan、拐了多大的彎。機會在1919nianchuxianle
，danquanshidaizainandaxiyangshang，henyaoyuan。yingguotianwenxuejiaaidingdundaizheyizhichongmanreqinghehaoqixindeguanceduichufale
，tamendeguancejieguoyuaiyinsitanshixianjisuandejieguoshifenwenhe，zhengshileaiyinsitanguangyixiangduilundezhengquexing。（付中梁）