5分钟的血月 本世纪最短月全食周六到来

Starting at 3:16 a.m. Pacific Daylight Time, the moon will begin moving into Earth's shadow. For the next hour and 45 minutes, that shadow will move across the moon and engulf it at 4:58 a.m. Pacific Time.

月亮将从太平洋时间凌晨3点16分开始进入地球的阴影。在接下来的1小时45分钟里，阴影将逐渐笼罩月亮并在4点58分达到食甚。

The total eclipse will only last four minutes and 43 seconds, and NASA says that makes it the shortest one of the century.

这次的月全食总共只有4分43秒，美国宇航局称这是本世纪最短的一次。

While people west of the Mississippi River will have the best view, at least a partial eclipse will be visible across the nation. But sunrise will interrupt the show on the East Coast.

整个美国都能或多或少看到这次月食，密西西比河以西是观看的最佳地点。不过，日出会影响东海岸的人们观看月食。

Parts of South America, India, China and Russia also will be able to see the eclipse, but it won't be visible in Greenland, Iceland, Europe, Africa or the Middle East.

南美部分地区、印度、中国和俄罗斯都能看到此次月食。而格陵兰、冰岛、欧洲、非洲和中东则无缘一见。

A lunar eclipse happens when the sun, Earth and moon form a straight line in space, with the Earth smack in the middle.

当地球位于太阳和月亮之间，三者同处一条直线时，月食就会发生。

The sun shines on the Earth and creates a shadow. As the moon moves deeper into that shadow, it appears to turn dark and may even appear to be a reddish color. Why red? Because Earth's atmosphere is filtering out most of the blue light. Some people have nicknamed the effect the "blood moon."

阳光照射在地球上形成了阴影。月球越接近阴影的中心，颜色就变得越深，甚至会变成红色。为什么是红色？因为地球大气层过滤了绝大部分蓝色。有些人管这种现象叫“血月”。

NASA says lunar eclipses typically happen at least twice a year, but this eclipse is the third in a series of four in a row, known as a "tetrad." The first was on April 15, 2017. The second was in September 2017, the next is Saturday and there will be one more, on September 28.

美国宇航局称月食通常1年发生2次。但此次月食将会是1年内连续4次月食（这种现象被称为tetrad，意思是4个一组）中的第3个。第1次发生在2017年4月15日，第二次是2017年9月，第三次是本周六，最后一次将在9月28日发生。