Aliens from other planets is an assumption. The reports and the phenomena is far more complex;
How UFO reports change with the technology of the times;
''In 1896, newspapers throughout the United States began reporting accounts of mysterious airships flying overhead. Descriptions varied, but witnesses frequently invoked the century’s great technological achievements.
Some sources reported dirigibles powered by steam engines. Others saw motorized, winged crafts with screw propellers. Many recalled a flying machine equipped with a powerful searchlight.
As technologies of flight evolve, so do the descriptions of unidentified flying objects. The pattern has held in the 21st century as sightings of drone-like objects are reported, drawing concern from military and intelligence officials about possible security threats.
While puzzling over the appearance of curious things overhead may be a constant, how we have done so has changed over time, as the people doing the puzzling change. In every instance of reporting UFOs, observers have called on their personal experiences and prevailing knowledge of world events to make sense of these nebulous apparitions. In other words, affairs here on earth have consistently colored our perceptions of what is going on over our heads.''
The wave of mysterious airship sightings that began in 1896 did not trigger widespread fear. The accepted explanation for these aircraft was terrestrial and quaint: Some ingenious eccentric had built a device and was testing its capabilities.
But during the first two decades of the 20th century, things changed. As European powers expanded their militaries and nationalist movements sparked unrest, the likelihood of war prompted anxiety about invasion. The world saw Germany—home of the newly developed Zeppelin—as the likeliest aggressor. Military strategists, politicians, and newspapers in Great Britain warned of imminent attack by Zeppelins.
The result was a series of phantom Zeppelin sightings by panicked citizens throughout the United Kingdom, Australia, and New Zealand in 1909, then again in 1912 and 1913. When war broke out in August 1914, it sparked a new, more intense wave of sightings. Wartime reports also came in from Canada, South Africa, and the United States. In England, rumors that German spies had established secret Zeppelin hangars on British soil led vigilantes to scour the countryside......''
