What exactly are UFOs?

Unidentified Flying Objects (or UFOs) are often described as nocturnal lights, cylindrical "cigar-shaped", saucer, bowl, or triangular shaped craft which appears to be under intelligent control. There are countless photographs and video footage of bright lights in the night sky, and small, reflective, metallic disks, even detailed craft (which are almost always hoaxed). Those who have allegedly had close encounters with UFOs describe the craft as being large, up to a 100 feet or more in diameter, with rotating parts, flashing, multicolored lights. In rare occasions, the actual occupants of the craft are seen. According to polls conducted in 1996 or 97, about 4 million Americans claimed to have been taken aboard alien craft against their will and undergone medical-like experiments, or have been raped. (Read more about abductions here.)

There is absolutely no conclusive evidence that alien life exists in outer space, let alone here on Earth. Astronauts are rumored to have seen luminous or metallic objects, but these are only rumors. There is some NASA footage which clearly shows objects flying on the surface of the moon, and Earth, but again, this is inconclusive and could be space junk or meteors.
Earthly evidence comes in the forms of implants which have been found in alleged abductees, cropcircles, and cattle mutilations. Numerous implants have been removed from abductees but have never been found to be extraterrestrial in origin, or tracking devices of any kind. Cropcircles have been hoaxed before, but others remain a mystery. However, scientific explanations exist about their formation. (Read more here.) Cattle mutilations have not been proven to be caused by aliens. Many logical theories exist, which you can read up on here.

Different races of extraterrestrials

THE GRAYS: The Grays are the most common of the aliens described by those who have encountered UFOs. The Grays are 3-5 feet tall, have large heads, thin arms and legs, large shiny, opaque black eyes, and are highly intelligent.

HUMANOIDS: Humanoid aliens or Nordics are commonly reported in Europe. These are attractive and usually friendly people who are more like "space brothers".

BEAST LIKE ALIENS: Commonly reported in South America and Africa, these include furry little monsters, giant blobs, cyclopes, and giant insects.

There are other aliens including reptilian beings. Few if no cases of alien encounters report Hollywood’s many renditions of aliens. The thought of "little green men from mars", or even ET, are unsupported in these cases. Not many people have been abducted by "Wookies" or Ewoks either.

Crop Circles
These concentric rings and patterns up to 100 feet in diameter have been appearing in farmers crop fields in England, United States, and other locations since the 1950's. A report stated that 98 circles appeared in 1988, 240 in 1989.

Crop circles are formed in maturing crops, the stems are partially flattened, and entangled or intertwined. The plants are all bent and face the same direction, clockwise or counter clockwise. The crops are never damaged, broken, or show signs of forced bending. The plants continue to grow normally throughout the rest of their growing cycle.

Lab analysis show that the DNA in the stems were actually "melted" in a process called denaturation. This occurs when the DNA is exposed to temperature around 70 - 75 degrees Celsius. The DNA breaks apart and, when allowed to cool, reforms, causing the plant to remain bent.

Read this article regarding crop circle formation using high powered lasers.

Researchers have ruled out all known probable causes including: hoaxes, whirlwinds, animals, wind vortices, and crop over-fertilization.

Crop circles always form rapidly at night (within an hour according to some reports). UFO sightings, moving orange lights, "whooshing" or warbling sounds usually preceed the formations of circles.

The majority of circles are formed around Stone Henge and other megalithic structures. They also appear to be aligned with ley lines.

The UFO Theory: Crop circle formation is similar to alleged UFO landing site reports where a circular swirling pattern is formed in grass, the grass remains unharmed, and is in inaccessible locations for vehicles.

Animal Mutilations

This global phenomena has baffled nearly everyone involved.

The first mutilation was reported in Colorado in September of 1967; the same year that Mothman terrorized and mutilated cattle in West Virginia, and a decade before the Chupacabra would be blamed for draining the blood and mutilating goats and livestock in Puerto Rico.

Most commonly, mutilated animals are cattle, but horses, goats, even deer and house-hold pets have been found dead with one or both eyes, tongue, genitals, anus, ears, utter, patches of skin, or other soft tissues removed. In most cases, the animal is completely drained of blood, with only a few drops or none at all located around the carcass. Organs are sometimes liquefied, and dead flies are found on the body.

Other (living) animals (including scavengers/carrion eaters) will avoid the carcass, acting extremely nervous or distressed around it. In naturally occurring deaths, other animals are not bothered by the dead body, and scavengers would gather around it and eat it.

There are no tracks around or near the carcass, even when the ground was soft after rain. Also, the wounds appear to be cauterized, suggesting the use of high-heat instruments.

Theories
Satanic Cults:
Some suggest the ones responsible are satanic cults. The problem with this theory is that the mutilations are too wide-spread, span 30 years, and would require a large amount of resources to execute.

Scavenging animals/predators: The Colorado Bureau of Investigation examined over 200 mutilation reports and concluded that the majority were caused by scavenging animals.

However, the way in which the animal died is inconsistent with how a predator would kill it. The drainage and absence of blood would be impossible for a predator to do.

UFOs: The absence of tracks, the mysterious nature of the act, and the coinciding UFO reports preceding mutilations suggest this is a sinister plan performed by aliens.

Government Involvement: Along with UFO sightings, black helicopters are also present before mutilations. Conspiracy theorists believe the government is conducting top secret chemical warfare experiments.

The weakness of this theory is that the government would have access to their own stock of cattle and would not necessarily need to use random cattle belonging to civilians. Also, the phenomena is too global to be conducted by any one government.

The Physics of Alien Craft

According to Bob Lazar, former government worker who claims he was hired to reverse engineer alien craft, the "flying disks" operate using an antigravity-propulsion system. The craft generates its own gravitational field, causing it to move forward at a perpetual down-hill motion. The "ships" are built for rapid travel (in space), and appear to wobble and move sporadically when hovering or traveling at slow speeds. Interestingly enough, the millions of eyewitness descriptions of the behaviour of UFOs, support this theory.

Government Involvement.

There are reports of crashed or downed alien craft worldwide. The most famous is the "Roswell Incident". Many alleged government documents have been released, stolen, or faked detailing the United States Government's secret involvement with extraterrestrials. There are supposedly many secret societies including the Jason Society, Men in Black, and others who keep knowledge suppressed. According to sources, the government has made a treaty with aliens, giving them the right to abduct humans in exchange for their technology.