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從現在到8月日落後，我們可見到西方低空有一顆特別明亮的星；它一天比一天亮，並於6月達到「最頂峰」。如果天朗氣清，這顆亮星必然會成為晴空的一個「地標」。但在5月16日的黃昏，它會突然熄滅23分鐘。但這次並非大衛高柏飛的魔術表演，而是罕有的天文現象—月掩金星；我們將看到一彎新月逐漸迫近金星，最終把它掩蓋。這個現象從北非經印度直至東南亞均可看到。但香港的地理位置較獨特，金星先會被月球的暗面遮蔽並在月球邊緣的背後掠過，於23分鐘後在新月其中一個月鈎旁邊重現。需要注意的是，金星重現時處於較低的地平高度，故應找西面沒有遮擋的地方觀測。
An Occultation of Venus
After sunset, from now until August this year, you would be able to see a very bright star hanging low in the western sky. The star is now gradually brightening and will be at its peak in June. This star is Venus and it will become a conspicuous "landmark" in the evening sky in the coming months. But on the 16th May something very special will happen. The landmark will disappear from our view for 23 minutes. This is not a trick by David Copperfield. It is a rare astronomical event called occultation. On that day the Moon will gradually approach Venus and pass in front of it. This event can be seen in North Africa, India and S.E. Asia. But Hong Kong is so specially placed that Venus will just pass behind the edge of the Moon's dark limb and reappear 23 minutes later near one of its cusp. ■甄枝強 資深天文愛好者
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