Discovering secrets of strange sights

北极光中出现浅蓝色螺旋，是UFO吗？

A light blue spiral appeared in the night sky on April 15 among the northern lights,

4月15日，夜空的北极光中出现了浅蓝色螺旋形物体，

fueling people’s interest in unidentified flying objects (UFOs).

这引起了人们对不明飞行物的好奇。

However, this time the science behind the event was simple.

其实，这一事件背后的科学原理很简单。

The cause of the spiral was the fuel released from the SpaceX rocket that had been launched from California, US, about three hours before the spiral appeared, reported The Guardian.

据《卫报》报道，在美国加利福尼亚州出现螺旋约三个小时前，SpaceX火箭发射升空，其释放的燃料导致螺旋的形成。

It was just a cloud of frozen fuel in the sky.

人们看到的蓝色螺旋物体，其实只是天空中的一团由冰冻燃料形成的云。

It’s also the third spiral, as similar shapes were observed in June 2022 and January this year,

人们都观察到了类似的形状，这已经是第三次了,2022年6月和今年1月，

both after the launch of SpaceX rockets, according to the Space Weather website.

在SpaceX 火箭发射后，据“空间天气（Space Weather）”网站报道。

On April 16, people in Shandong province observed a green object with a long golden tail flying across the sky.

4月16日，我国山东省民众观测到一个带着一条长长金色尾巴的绿色物体飞过天空。

Qingdao Aishan Observatory confirmed later that it was a piece of meteor.

青岛艾山天文台后来证实那是一颗流星。

“Even the aliens are coming for the local barbecue,” an internet user joked as barbecue in Zibo, Shandong, has recently become popular.

一位网友调侃说：“甚至外星人都来吃淄博烧烤了”。那时，山东淄博烧烤火爆全网。

Strange sights in the sky never cease to attract people’s interest.

天空中的奇怪景象总会引发人类的好奇。

So what else could the “UFOs” we see in the sky be?

那么，我们在天空中看到的“不明飞行物”还可能是什么呢？

People may believe that they have seen a UFO right before sunrise or after sunset.

在日出前或日落后，经常有人观测到所谓的“不明飞行物”。

The “UFO” may be glowing and climbing, as if it’s getting out of Earth’s atmosphere.

该物体可能一边发光一边缓缓升空，仿佛正在脱离地球大气层。

However, they may be just airplanes.

然而，其实可能只是飞机。

At those times, the sky is dusky when observed from Earth,

因为在这些时刻，从地球上看，天空是昏暗的，

but high in the sky,there is still light that shines on the aircraft, which is why it’s glowing.

但在高空中，依然有光线照射在飞机上，所以它才会发光。

Also, the shape of the airplane isn’t clear when it’s climbing, leading to confusion among observers.

此外，当飞机在上升时，其形状并不清晰，导致观测到的人产生误解。

Something else that can shine strangely in the sky is a noctilucent cloud, which can be mistaken as a UFO.

在天空中还可能观测到另一种能够奇异发光的物体——夜光云，它有时候也被误认为是“不明飞行物”。

Usually appearing after sunset, these clouds are formed when the temperature in the atmosphere is at its lowest.

夜光云通常在日落后出现，其在大气温度最低的时候形成。

Due to the high altitude, water vapor can freeze into clouds of ice crystals, which then reflect the sunlight.

高海拔让水蒸气凝结成冰晶云，然后反射阳光。

以上文章内容选自《21世纪学生英文报》高二908期