The vernal equinox, however, occurs when the center of the sun crosses the Equator.

当太阳中心横过赤道之时，便是春分。

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As the Sun crosses the celestial equator heading south, spring begins in the southern hemisphere and autumn in the north.

当太阳在天赤道上掉头向南的时候，南半球的春天开始而北半球则是秋天。

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At each equinox, the sun crosses the Earth's equator, making night and day of approximately equal length on most of the planet.

在每一年的春分点上，太阳横跨着地球上的赤道，使得地球上大部分地区的白天和夜晚的时间接近相等。

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First spotted last week, it seems to be diminishing but could still produce more surprises before it crosses to the far side of the sun on April 5.

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