网友在Quora上问：What are the fascinating things that happen once in a year?有哪些事情是一年发生一次的奇妙事情？

Chichen Itza回复：

Mexico: The Illuminated Snake

墨西哥奇琴伊察(玛雅古城遗址)：羽蛇阴影

It actually happens on both solstices, that the sanke is lighten up because of the shadow that falls around it.

这个现象只发生在春秋分，日出日落时，建筑的拐角在金字塔北面的阶梯上投下羽蛇状的阴影。

Xu Beixi回复说：

The Christmas Island crab migration, where these little critters make their way from the forest to the ocean, in which they lay their eggs.

澳大利亚圣诞岛红蟹大迁徙，无数的红蟹从森林爬到海洋去产卵。

Here's a baby crab:

幼年的红蟹

And here they are, blocking the roads:

数量庞大，占领整条马路。

So if you're ever visiting,

如果你去旅游会看到这样的提醒栏。

Sandeep Yadav回复说：

Naga Fireballs

那加火球：每年十月从湄公河里飞起来的火球

What would you do if you were walking along a tropical river at night and it suddenly began burping up egg-sized balls of red light? It happens every year in October along the Mekong river.

想象你夜晚在河边散步，突然看到从水里升起来一个个鸡蛋大的火球你会有什么反应?每年十月湄公河就会出现这种神奇的现象。

Vincen Mathai回复说：

The AVIAN HARAKIRI of Jatinga, India.

印度杰廷嘉群鸟自杀现象

This is a phenomenon that occurs at Jatinga between September and November each year. During these late monsoon months, several migratory and local birds commit mass suicide at the village. Just after sunset, between 7 and 10 pm, hundreds of birds descend from the sky, plummeting to their deaths by crashing into buildings and trees. Since birds aren’t known to be suicidal, the phenomenon has baffled villagers, visitors and scientists alike. For many years, locals believed that evil spirits living in the skies were responsible for bringing down the birds .

每年九到十一月份之间，只要到了季风时节晚期，都会有鸟群在杰廷嘉“集体自杀”，包括当地的鸟类以及其他候鸟。在日落后的19点至22点之前，数以百计的鸟儿会从空中飞下来，撞到墙上或树上死亡。鸟类不是具有自杀性的物种，所以这一现象让村民、游客、科学家们都感到费解。多年以来，这里的村民都认为是空中有邪恶幽灵存在，才导致群鸟自杀。

Ornithologists have made many credible theories but the mystery is till yet to be explained properly.

鸟类学家提出了很多猜想，但至今仍唯有合理的解释。

Gokul Nair回复说：

Manhattanhenge

曼哈顿

It is an event during which the setting sun is aligned with the east–west streets of the main street grid of Manhattan, New York City.

落日直直的从曼哈顿东西大道的尽头沉下，像被镶嵌在两旁高耸的大楼之间。

严格说来时一年两回，夏至的日出和日落。

Samidha Paroha回复说：

Check out this street in Bonn, Germany. Someone who sees it in autumn would probably think it's just another normal street. However, to appreciate its true marvel, you have to visit this place in Bonn during a particular span of 20 days in the spring.
德国波恩的这条小径。若你秋天来看它，它并没有什么稀奇之处，但是你要是在春天的特定那二十天到这个地方，你会觉得恍若置身仙境。

For around two-three weeks every year, this street in Bonn, Germany, becomes a popular attraction for tourists as it magically transforms into a spectacular view where cherry blossoms cover up the entire street making a tunnel, giving the street a heavenly appearance. Have a look.

大概每年春天的两到三周，无数樱花开满枝头，搭成了一条花的走廊。

Patrick Crosset回复说：

迁徙