The heliopause was expected to be a rather sharp boundary between the sun's domain and interstellar space.

太阳风顶层曾被认为是处在太阳系区域和星际宇宙之间一层电磁波动极其强烈的区域。

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The rocket experimental data indicated that the layered dusty plasma structure has a sharp boundary in the summer polar mesopause.

火箭探空实验观测结果显示，极区夏季中层顶尘埃等离子体分层中存在着稳定的锐边界结构。

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Explanation: No sudden, sharp boundary marks the passage of day into night in this gorgeous view of ocean and clouds over our fair planet Earth.

说明：在这张绚丽的影像中没有突然、明显的界限显示地球白天进入夜晚的经过，影像拍摄的是我们地球上空拍摄的海洋及云朵。

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It is possible to draw too sharp a boundary between prophetic and merely symbolic images, between mad vision and coded cartoon.

NEWYORKER: The Big Reveal

The return of Kevin Pietersen galvanised England and he batted beautifully and although he was clearly hampered by his Achilles injury and in no mood to run sharp ones or twos, he found the boundary five times, and cleared it three times as England improved on their 14 fours against the Dutch with 18 fours and six sixes here.

BBC: Jonathan Agnew column