This is a tricky subject for ufologists in general, although there is a classification model, no physical evidence of them. All types of settings are made through evidence collected that may or may not be correct.
items analyzed reports of contact for the classification is the anatomical shape, most humanoid with minor variations, differing from us. There is the assumption that some changes might be part of the same species as the human race has many characteristics of their height and color.
In a study by Eric Zurcher in the book "Les apparitions d'humanoids," he described the extraterrestrial sightings reported in up to 1973 in 08 types: identical to humans, short stature, hairy, men with long hair; beings helmets; Cyclops; undefined forms and beings with geometric shapes or amorphous. Ufologist Spaniard Salvador Freixeda also created a classification differentiating beings in 05 types, according to the contacts or source.
Currently the most widely used classification by ufologists of the series, determined by estimating the percentage of sightings collected are listed below with the letters of the Greek alphabet:
Alfa - are beings of short stature (1.00 to 1.40), grayish skin, big head out of proportion to the body. Usually have large eyes, black and seemingly without pupils. They have a personality sometimes shy or very active, intelligent and pointed as scientists. Present in about 65% of reported cases and are the most widely covered by media speculation.
Beta - like humans, measuring 1.60 to 2.00 meters. Are reported in 20% of sightings. The resemblance is so they can walk freely in our midst undetected. Owners of great beauty and wisdom present themselves peacefully.
range - have a height above normal, 2.00 to 4.00 meters. Arise in 8% of cases. Always friendly.
Delta - are often hairy or detailed as some similarity with robotics. Are reported in only 3% of cases filed. Counted by the details have high mental capacity.
Omega - things that have no physical form, but energy. These are most difficult cases to findings in reports collected by ufologists of the series, only 2% of cases. They are beings made of light and spiritual, in many cases appear floating, being confused with angels.
Sigma - these beings are very small, with reports pointing to a height around 15 cm. These are reported in less than 1% of contacts.
This classification is not yet own, since there is great diversity, but it is applied to the identification within the aesthetic standards that we understand.
In the case of beings classified as Omega , the explanation for its formation energy is that these beings possess a frequency ¹ faster than humans, acting in parallel worlds ² or higher. Because they operate in other more subtle dimensions ³ not unnoticed by us, manipulating the different frequencies, because it may be directly involved in our planet / dimension ³ .
¹ frequency: Explanation the site ( http://mental-2.blogspot.com ) - text "Frequencies and Vibration" parallel worlds
²: explanation on the site ( http://mental-3.blogspot. with ) - text "M Theory (Multiverse)"
³ dimensions: explanation on the site ( http://mental-3.blogspot.com ) - text "M Theory (Multiverse) "