2. 飞机（Airplanes）
Here's proof that anything funny-looking in the sky can cause an uproar. This past Monday, most of the U.S. woke up to reports that a mystery missile had launched off the coast of California. The sightings were spurred by video of a condensation trail, or contrail, streaking through clouds lit up by the rising sun. No one could conclusively say what it was at the time—officials at the Department of Defense reported no scheduled missile launches, NORAD and USNORTHCOM detected no foreign activity and the FAA hadn't cleared any commercial space launches in the area. After a thorough investigation, many experts now believethat the streak was a – wait for it – a run-of-the-mill jet aircraft contrail that happened to hang around longer than usual. Contrails appear most vivid around sunrise or sunset, and it's not uncommon that one showing up in an unexpected location will generate whispers of a UFO or experimental military aircraft.
可以证明，天空中任何有趣式样都可以引起一片哗然。在刚刚过去的星期一，大多数的美国人早晨醒来，就听到报道，说是有一枚神秘的导弹在利福尼亚海岸发射升空。凝结尾迹的视频鼓动了所看到的情景，使它透过上升太阳所照亮的云层而加上了条纹。当时没有人能最后地说，这是什么？——国防部的官员报告没有安排导弹发射，北美防空联合司令部和美国北方司令部没有检测到国外的有关活动，(美国)联邦航空局没有明确在这个地区里有什么商业上的空间发射。在经过彻底调查以后，许多专家认为所看到的线条是——等着——是一个运行着的米尔喷气飞机轨迹，它偶然发生，比平常有较长的流连时间。凝结尾在日落和日出时，会显露得非常生动，这种情况并不少见，一个意外的位置上所显露出来的现象将产生与UFO或实验用军事飞机相类似的低低声音。
Lights in the sky, especially when viewed by pilots, can also cause a stir, but are almost always revealed to be running lights of other aircraft, or flares dropped by weather research craft.
天空里的光，特别当被飞行员看到的，也可以引起骚动，但它几乎总是被揭露为其他飞行器运行时的灯光，或者是气候研究用飞行器所放下的照明弹。
