帕尼迪斯沙丘上的日晷，立陶宛库尔斯沙嘴 Sundial on Parnidis Dune, Curonian Spit, in Lithuania (© amoklv/Getty Images)

帕尼迪斯沙丘上的日晷，立陶宛库尔斯沙嘴 Sundial on Parnidis Dune, Curonian Spit, in Lithuania (© amoklv/Getty Images)

It's time for spring

This 40-foot sundial stands atop the Parnidis Dune, one of the scenic highlights of Curonian Spit, a UNESCO World Heritage Site shared by Lithuania and Russia. Built in 1995, the sundial was damaged by a hurricane a few years later and rebuilt in 2011. It accurately tells time by creating shadows on the steps, with notches for hours and half hours, as well as months, equinoxes, and solstices.

March 20 marks the spring (or vernal) equinox in the Northern Hemisphere, meaning that for the next six months daylight hours will outlast nighttime darkness. When it's winter in the Northern Hemisphere, those of us above the equator are tilted away from the sun, giving us shorter days and longer nights. In summer, we're tilted toward the sun, but the equinox is right in between. It's the moment during Earth's annual revolution around the sun when its axis is neither tilting away nor tilting toward the sun, giving everyone on the planet an equal split of day and night. This phenomenon happens twice a year—in March and again in September. In the Southern Hemisphere, everything's flipped. There, it's the autumnal equinox today—and, yes, winter is coming.

春天到了

这座40英尺高的日晷矗立在帕尼迪斯沙丘上，这座沙丘是立陶宛和俄罗斯共同拥有的联合国教科文组织世界遗产库伦吐谷（Curonian Spit）的一大亮点。日晷建于1995年，几年后被飓风破坏，2011年重建。它通过在台阶上创建阴影来准确地显示时间，刻痕为小时和半小时，以及月份、分点和至点。

3月20日是北半球的春分（或春分），这意味着在接下来的六个月里，白天的时间将比夜间的黑暗时间还要长。当北半球是冬天的时候，我们这些在赤道以上的人会远离太阳，使我们白天变短，夜晚变长。在夏天，我们向太阳倾斜，但春分正好在两者之间。这是地球每年绕太阳公转的一个时刻，它的轴既不向太阳倾斜，也不向太阳倾斜，使地球上的每个人都有一个平等的日夜之分。这种现象每年3月发生两次，9月又发生一次。在南半球，一切都在翻转。在那里，今天是秋分，是的，冬天来了。