Some Popular ideas for explaining UFO

To account for unsolved UFO cases, a number of explanations have been proposed by both proponents and skeptics.

Among proponents, some of the more common explanations for UFOs are:

* The Extraterrestrial Visitation Hypothesis (ETH) (most popular)
* The Interdimensional Hypothesis
* The Paranormal/Occult Hypothesis
* The hypothesis that they are time machines or vehicles built in a future time.

Similarly, skeptics usually propose one of the following explanations:

* The Psychological-Social Hypothesis
* The man-made craft hypothesis
* The unknown natural phenomena hypothesis, e.g. ball lightning, sprites
* Peter F Coleman advanced a meteorological theory that many so-called UFOs or unexplained lights seen now and in the past are actually instances of visible combustion of a fuel (e.g. natural gas) inside an atmospheric vortex. He has argued his case in his book, Great Balls of Fire-a unified theory. [53] This vortex fireball theory was first published in Weather[54] and later in the Journal of Scientific Exploration [55]
* Earthquake lights/Tectonic Strain hypothesis

There are myriad explanations being put forward all the time:

* One explanation is that (some) UFOs are misidentified "shiny-bodied insects"[56]
* Another is the Extraterrestrial energyzoa theory
* That they are caused by "floaters", a medical condition affecting the eyes, which are considered "normal".

Usually a combination of explanations is cited to explain all cases, and even proponents will sometimes invoke skeptical explanations, such as man-made military aircraft, to attempt to account for some unsolved cases.