What is the winter solstice, and why do we have it?

什么是冬至？为什么有冬至这个节气？

"Earth's axis¹ is tilted² 23.5 degrees relative to its orbit, and on December 21, Earth will be at the point in its orbit when the North Pole is tilted at its maximum away from the sun," Schneider told CBS News. "The effect of this in the Arctic is completely in darkness as Earth spins that day."

施奈德说：“地轴相对于自转轨道的倾角为23.5度。12月21日，地球的北极距离太阳最远。这会导致当天北极圈地区完全见不到太阳。”

For those of us in the Northern Hemisphere, it's the day with the shortest amount of daylight — less than 12 hours — and our longest night of the year. However, that's not the case for everyone. While it's winter for those of us in the Northern Hemisphere, people in the Southern Hemisphere experience it as their summer solstice with the longest stretch of daylight.

对北半球的人们来说，冬至这一天白昼最短，不到12小时，夜晚最长。但并不是对所有人都这样。北半球经历寒冬时，南半球在这一天迎来白昼最长的夏至日。

When does the winter solstice occur?

冬至在哪天？

The Earth's North Pole will be tilted farthest from the sun at 11:27 am ET on Thursday, Dec. 21, 2017, according to the National Weather Service.

根据美国国家气象局的数据，今年的冬至发生在美国东部时间2017年12月21日上午11点27分（北京时间2017年12月22日零点27分），此时北极距离太阳最远。

Why isn't the winter solstice on the same day each year?

为什么每年的冬至都不是同一天？

The date of the winter solstice varies from year to year for people in different time zones. It typically occurs around Dec. 21 or 22, though on rare occasions it can be as early as Dec. 20 or as late as Dec. 23, according to the Weather Channel.

根据天气频道的数据，对不同时区的人们来说，冬至的日期每年会有变化。多数年份的冬至日都在12月21日或者22日，偶尔提早到20日，或者错后到23日。

That's because our calendars aren't a precise match to the solar year.

这是因为日历与阳历并非完全吻合。

Schneider writes: "Earth takes about 365 1/4 days to orbit the Sun. Next year, the moment of the solstice will be about 6 hours later at 5:23 pm ET. In 2019, it will be at 11:19 pm ET, so for people living in Puerto Rico and other time zones to the east, the date of the solstice will be on the 22nd."

施奈德写道：“地球围绕太阳公转周期为365又1/4天。明年的冬至比今年大约迟6个小时（美国东部时间下午5点23分），后年又推后到美国东部时间晚上11点19分。所以对于居住在波多黎各及以东时区的人们来说，冬至日期是22日。”

Is the winter solstice the coldest day of the year?

冬至日是全年最冷的一天吗？

The winter solstice is not normally the coldest day of the year. There is actually a lag between the shortest day of the year and the coldest average temperatures, the National Weather Service reports.

美国国家气象局报告说，冬至日通常不是全年最冷的一天。白昼最短的一天与平均气温最低的一天之间其实有延迟。

"The coldest time usually comes a month or two later because even though the amount of solar heating is beginning to increase, it isn't yet enough to reverse the cooling," Schneider says. "This effect, called 'the lag of the seasons,' is similar to how when you turn down the heat while you're cooking — the pot won't immediately reach its coolest temperature."

施奈德说：“全年最冷的时候通常比冬至日晚一两个月，因为尽管日照开始变长，但仍不足以改变寒冷的趋势。这称为‘季节延迟’，就像你做饭时关火以后，锅的温度不会马上降低。”

Will shadows on the day of the solstice be longer?

冬至日这天影子会变长吗？

Noontime shadows on Thursday will be longest for those of us in the Northern Hemisphere because the sun doesn't rise as high in the sky. The closer you are to the Arctic, the longer the shadows (and the shorter your day) will be.

对北半球的人们来说，冬至这天中午时影子最长，因为太阳的高度最低。越靠近北极圈，影子越长，白昼时间越短。

Why doesn't the earliest sunset come on the shortest day?

为什么白昼最短的当天日落并非最早？

The winter solstice may be the shortest day of the year, but that doesn't mean you'll have an early sunset. The exact date of the earliest sunset depends on your latitude³, so it's not the same for everyone.

冬至日是全年白昼最短的一天，但并不意味着日落最早。日落最早在哪天取决于你所在的纬度，对每个地方的人来说都不同。

Ancient Chinese people divided 81 days after winter solstice(regarded as coldest time of the year) into 9 parts. Many used "double-nine" diagrams to count the days to spring, either by recording⁴ the weather or writing one stroke of a character on a daily basis.

中国古人将冬至日后的81天分为九个“数九天”，视为全年最冷的一段时间。民间有贴九九消寒图的习俗，用于计数春天来临之前的日子，有些是通过记录天气，有些则是通过每日写一笔来计算数九天。

China has developed an unique festive⁵ food culture throughout the years. Eating dumplings is a common folk custom for many Chinese on the day of winter solstice, especially those living in the north.

冬至经过数千年的发展，形成了独特的节令饮食文化，吃饺子则是多数中国人冬至的习俗。在北方尤其突显。

When midwinter comes, vital movement begins to decline and calm down. In this period, eating an appropriate amount of nuts, such as peanuts, walnuts⁶, chestnuts⁷, hazelnuts and almonds, is good for one's body.

冬至来临后，人们开始减少活动。这段时间食用适量坚果对身体非常有益，比如花生、核桃、栗子、榛子和杏仁。

People in Suzhou, Jiangsu province, are accustomed to eating wontons in midwinter. According to legend, during the midwinter feast 2,500 years ago, the King of Wu was disgusted with all kinds of costly⁸ foods and wanted to eat something different. Then, the beauty Xishi came into the kitchen to make "wontons" to honor the king's wish. He ate a lot and liked the food very much. To commemorate⁹ Xishi, the people of Suzhou made wontons the official food to celebrate the festival.

江苏苏州的人们习惯在冬至吃馄饨。根据历史传说，在2500年前的冬至时节，吴国国王厌倦了所有的昂贵美食，想吃些特别的口味。为迎合吴王的心愿，美女西施去厨房做了一碗馄饨。吴王很喜欢，吃了一大碗。为了纪念西施，苏州人会在冬至做馄饨庆祝节日。

In places such as Shanghai, people eat tangyuan, a kind of stuffed small dumpling ball made of glutinous¹⁰ rice flour to celebrate Winter Solstice.

在上海等地，人们吃汤圆庆祝冬至。汤圆是圆形的糯米粉团，中间塞满馅料。

In Yinchuan, Ningxia Hui autonomous¹¹ region, people call midwinter the "Ghost Festival". On that day, it is customary for people there to drink mutton and vermicelli soup and eat the dumplings in the soup. They give the midwinter soup a strange name: "brain" and share it with their neighbors.

在宁夏银川，大家称冬至为“鬼节”。这天的习俗是吃羊肉粉汤饺子，此外他们还给这道美味起了个古怪的名字“头脑”。粉汤饺子做好后还要给邻居端上一碗。

During the Winter Solstice, Hangzhou residents traditionally eat rice cakes. In the past, before the approach of the winter solstice, every household would make the cakes to worship their ancestors or use as gifts for relatives and friends.

杭州居民有冬至吃年糕的传统。过去每家每户都会在冬至到来前制作年糕来供奉先人或者馈赠亲友。

In some regions south of the Yangtze River, the whole family gets together to have a meal made of red-bean and glutinous rice to drive away ghosts and other evil things.

在我国长江流域以南的一些地区，在冬至之夜有全家欢聚一堂共吃红豆糯米饭来驱避疫鬼的习俗。

Taiwan residents keep the custom of offering nine-layer cakes to their ancestors. People with the same surname or family clan¹² gather at their ancestral temples to worship their ancestors in order of their ages. After the sacrificial ceremony, there is always a grand banquet.

台湾地区还保存着冬至用九层糕祭祖的传统。同姓或同家族的人们在祠堂前相聚，按辈分祭祖。祭祖仪式后还会举办盛宴。