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通過安全濾鏡，我們可以觀測到熟悉的太陽，這部分的太陽白而光亮，天文學家稱之為「光球層」，有時我們更可在光球層的表面找到太陽黑子。光球層的外圍還有較薄、較暗、難以觀測到的太陽外大氣層，這些看不見的太陽部分只會在日全蝕的短短數分鐘內暴露它們的行藏。英國天文學家洛克爾（自然科學雜誌創辦人）在1868年觀測日全蝕時，發現了光球外面的「色球層」，並在色球層找到一種新元素—「氦」。色球層大約有2千公里厚，實際是一層針刺狀的小火舌覆蓋在光球的上面，這些小火舌稱為「針狀物」，針狀物從生成到消失只有約10分鐘的光景。從光球表面，經常有巨大的「日珥」，穿透色球層直達太陽最外圍的「日冕」，超巨形的日珥可高達35萬公里。
The invisible sun
The part of the sun that we commonly see through safety filter is called the photosphere (ball of light). We have no way of knowing what it is actually like beneath the photosphere. But the layers that lie above do manifest their presence from time to time when the moon blocks the sun from our view completely. In fact it was during the 1868 total solar eclipse that Norman Lockyer (British scientist and founder of the science periodical, ‘Nature’) first discovered a thin layer of solar atmosphere just above the photosphere. This layer stands out pinkish and Lockyer named it the ‘chromosphere’ (ball of colour). Lockyer also shared a joint credit with Janssen (French scientist) for the discovery of a hitherto unknown element, helium, in the chromosphere. ■甄枝強 資深天文愛好者 ■圖片：ESA, NASA
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