I will admit to being a science fiction fan. I believe the physical make up of what alien beings will look like, if eventually encountered should be studied. I will examine the reported information from past encounters. Then I will use this information to extrapolate using Darwinian style evolution to come to a prediction of what aliens would like. This information can be helpful to future astronauts. I will attempt to remove this subject from the realm of the esoteric to provide useful information for space travellers and those having alien encounters while on earth.
Lets examine some cases of extraterrestrial encounters or visits. There have been hundreds of reports of individuals being abducted by aliens. The reports follow a familiar pattern. The abductees were either sleeping or going about their business when all of a sudden they were abducted. They awoke and saw aliens looking and performing tests on them. The aliens were often described as having unusually large heads for the size of their bodies. They had slanting eyes and flat noses. The color of the alien was a dark green or grayish.
The aliens at the well known Roswell incident were said to have had greenish colored bodies. The Roswell incident happened around July of 1947 when an unidentified object crashed at Roswell, New Mexico. Many investigators do not believe that the object that crashed was an experimental high altitude balloon as the government would have us believe. Some UFO investigators believe that the crash victims at Roswell were hidden by the US government and studied. The aliens were reported to be small with slanted eyes and greenish in color.
I would like in the following analysis to explain why the aliens the future astronauts may encounter will be green in color. The reason I believe is that the aliens are breathing by photosynthetic respiration through the skin. This is the way plants breathe and very efficient on long space voyages. All the aliens would need to survive is bright light, water and carbon dioxide. This type of photosynthetic respiration is backed up by the fact that descriptions of the inside of alien spacecraft that have landed are described as brightly lite.
Photosynthesis converts the suns light to cellular energy to keep the aliens alive. Their skin contains chlorophyll the active ingredient of photosynthesis. Basically their skin is performing the same function as a plant leave. They may come from planets where the greenhouse effect is so advanced that they evolved to survive. The aliens nose slits may be vestiges of their former oxygen breathing ancestors and non-functional or slightly functional.
I believe an open mind is needed in regard to aliens. If our astronauts do meet them I hope their friendly. We can learn from each other.