千年等一回—日環(huán)食歸來

Ring of fire' solar eclipse to occur Sunday, May 20

日環(huán)食將于5月20日出現(xiàn)

A partial solar eclipse photographed by the joint Japanese-American Hinode satellite. (Hinode/XRT)

被日美聯(lián)合衛(wèi)星“日之出”所拍攝到的一顆日偏食

(Space.com) Skywatchers in East Asia and the western United States should circle Sunday (May 20) on their calendars. That's when a solar eclipse will block out most of the sun, leaving a spectacular "ring of fire" shining in the sky for observers located along the eclipse's path.

東亞和美國西部的觀測者應(yīng)該在日歷上圈上周日(五月20日)這天。這一天日食會遮住太陽的大部分，只留下一個壯觀的“火環(huán)”在天空閃爍，位于日食運(yùn)行軌跡上的觀測者都有機(jī)會觀測到這一景象。

The event is what's known as an annular solar eclipse -- from the Latin "annulus," meaning "little ring" -- and its full glory should be visible from much of Asia, the Pacific region and some of western North America, weather permitting. At its peak, the eclipse will block about 94 percent of the sun's light.

這一景象就是我們所說的日環(huán)食，拉丁語“annulus”意思為“小環(huán)”。如果天氣條件允許，位于亞洲，太平洋地區(qū)及西北美一些地區(qū)的觀測者將有幸目睹這一壯觀景象。日食最大時會遮住94%的太陽光。

Other parts of the United States and Canada will still see a partial solar eclipse, without being treated to the ring of fire effect, though the East Coast will miss the event since the sun will have set before it begins. The eclipse will occur in the late afternoon or early evening of May 20 throughout North America, and May 21 for observers in Asia.

雖然東海岸的觀測者會因為太陽在日食開始前就日落而錯過這次日食，但美國和加拿大其他地區(qū)的觀測者仍然可以看到日偏食，只不過不是火環(huán)狀。日食將在北美5月20日的傍晚時分或晚上出現(xiàn)。

Solar eclipses occur when the moon comes between Earth and the sun, casting a shadow on our planet. When the moon lines up perfectly with the sun and blots out all of its light, the result is a total eclipse. Partial eclipses cover only part of the sun's face.

當(dāng)月亮運(yùn)行到地球和太陽之間時，日食就會出現(xiàn)，并在地球上投下月影。當(dāng)月亮和太陽完全成一條直線并遮住太陽時，就形成了日全食。日偏食即月亮只遮住了部分太陽。

Annular eclipses are similar to total eclipses in that the moon lines up with the sun dead-on. But in this case, the moon is close to apogee -- the farthest point from Earth in its elliptical orbit around our planet -- so it's a smidge too small in the sky to cover the solar disk completely. As a result, a ring of bright sunlight will still blaze around the moon's circumference.

日環(huán)食與日全食的形成是相似的，即在月亮與太陽完全成一條直線時才會發(fā)生。但在這種情況下，月亮接近最高點(diǎn)——位于它橢圓軌道上的最遠(yuǎn)點(diǎn)。而這時它的表面積太小不足以完全遮住太陽表面，就形成了一個在月亮周圍發(fā)光的日光環(huán)。

Like other types of solar eclipses, annular eclipses are spectacular but potentially dangerous skywatching events. Care must be taken to observe them properly, or serious and permanent eye damage -- including blindness -- could result.

和其他種類的日食一樣，日環(huán)食是很壯觀的景象，但同時對觀測者來說卻也存在潛在危險。觀測者要十分注意以正確的方式進(jìn)行觀測，否則眼睛會被嚴(yán)重灼傷或?qū)е掠谰檬鳌?/p>

Warning: Never look directly at the sun, either with telescopes or binoculars without the proper filters.

提醒：不要直接用眼睛觀看，要使用望遠(yuǎn)鏡或者無過濾片雙筒鏡。

To safely observe the May 20 annular eclipse, you can buy special solar filters to fit over your equipment, or No. 14 welder's glass to wear over your eyes. Do NOT use standard sunglasses or any kind of homemade sun-shading contraption.

安全起見，為觀測5月20日出現(xiàn)的日環(huán)食，你可以購買特殊的太陽濾鏡并將其安裝在觀測設(shè)備上或者佩戴No. 14 welder's眼鏡。不要使用普通太陽鏡或者任何自制的遮陽裝置。

The safest and simplest technique is perhaps to watch the eclipse indirectly with the solar projection method. Use your telescope, or one side of your binoculars, to project a magnified image of the sun's disk onto a shaded white piece of cardboard.

最安全和最簡單的方法可能就是通過太陽投影來觀測日食。用你的望遠(yuǎn)鏡或者雙筒鏡的一面在一塊白色的紙板上投影一個放大的太陽圖像。

The image on the cardboard will be safe to view and photograph. Be sure to cover the telescope's finder scope or the unused half of the binoculars, however, and don't let anybody look through them.

觀察和拍攝紙板上的圖像是安全的。確保要遮住望遠(yuǎn)鏡的可視范圍部分或者雙筒鏡不使用的一面，不要讓任何人通過望遠(yuǎn)鏡和雙筒鏡來觀察。