Slow sunrise sweeping across moon’s near side

When you see a waxing moon in the evening sky, from one night to the next you are seeing the line of sunrise creeping across the moon’s near side (the side facing Earth). Alexander Kozik of Davis, California captured the lunar sunrise in this sequence of images from February 17, 2013, in only two hours. It’s subtle, but can you see it? Look carefully at the terminator line – or line between light and dark on the moon. Notice its relationship to lunar craters, and especially notice how sunlight is illuminating the crater walls along the terminator, as the sun rises higher in the lunar sky.

Because the moon rotates in the same length of time it takes to orbit Earth (about one month, or “moonth”), sunrise on the moon is a much slower event than here on Earth. In other words, a full day-night cycle on the moon lasts about an earthly month, and – for any one point on the moon’s surface – sunrise comes only that often.

Read more: Understanding moon phases

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