Finally, the balloons are beautifully placed across the sky, but the red balloon in the upper left of the frame is the final, key element to the success of the image.
最后，气球美丽地横跨在天空里，然而画面左上角的红色气球是成功拍摄这张照片决定性的关键元素。
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Like a conventional mirror, a solar balloon of this sort must be turned to face the sun as it moves through the sky, and Cool Earth is testing various ways of doing this.