The Alpha Centaurians are a humanoid race possessing aquatic qualities about them such as gills and webbed limbs to allow surviving in their oceanic environments. They have a luminous, bluish-gray skintone and appear to vary significantly in height. Being a naturally-aquatic species, they are rumored to currently inhabit the deep ocean depths of Earth, and are thereby believed to be the species piloting the UFOs occasionally seen (primarily by Navy personnel) entering or emerging from the oceans. They are stated as vibrating and resonating on the band of violet light.
They are said to possess vast scientific and technical prowess that is amongst the highest quality in the universe, and are stated to not only be accredited with cattle mutilations but also possess such advanced weapons systems that other species are afraid to war with them. Evn so, they are very theoretical: part of their mission statement on Earth is to help raise its local populace's scientific, technical and theoretical knowledge, although they are also claimed to be here to enlighten mankind's consciousness. It is possible that this mental enlightenment is to allow Earthlings to actually comprehend their knowledge, due to its vast superiority to that on Earth.
Apparently telepathic in nature, they attempt to make their knowledge known to others by telepathically linking up with some of mankind's most advanced scientists, although since they are so incredibly intelligent by comparison and have such a high vibration, it is occasionally difficult for them to ground their ideas to the Earthly plane. Because of this they have allied with the Sirians who are quite good at bridging this gap due to being very good at the practical application of ideas, as well as making these theories usable for a third dimensional society such as that of Earth. As such, the Sirians operate as the workers and doers of the Earth for the Alpha Centaurians.