An illustration depicting the "little green men" described by Billy Ray Taylor, recorded in Close Encounter at Kelly and Others of 1955. Image from J. Allen Hynek Center for UFO Studies

Why are aliens so often depicted as “little green men” with bulbous heads and oversized eyes?

The mythology began, in part, on the night of August 21, 1955, when a large extended farm family called the Suttons arrived breathlessly at the Hopkinsville police station in southwestern Kentucky. Their story of a terrifying siege by otherworldly beings would become one of the most detailed and baffling accounts of an alien close encounter on record—notable for the large number of witnesses (nearly a dozen), the duration of the encounter (several hours) and the close proximity between the witnesses and creatures (sometimes just a few feet away). The incident quickly became regional and even national news.

The alleged encounter occurred on the Suttons' farm in the tiny rural hamlet of Kelly, Kentucky, where the family lived in an unpainted three-room house without running water, telephone, radio, TV or books. Of all the details of their story—the UFO landing and the appearance of small alien creatures—one fact is indisputable: When the eight adults and three children arrived at the nearby Hopkinsville police station at about 11 p.m., they were genuinely terror-struck.

“These aren’t the kind of people who normally run to the police for help,” police chief Russell Greenwell later told investigators. “What they do is reach for their guns.” Yet here they were, women and children hysterical and one man with a pulse of 140 beats per minute, measured by an investigator.

READ MORE: How Betty and Barney Hill's Alien Abduction Story Defined the Genre

Small metallic humanoids, impervious to bullets

Image from J. Allen Hynek Center for UFO Studies

According to accounts given to the police, at about 7 p.m. on the hot Sunday evening, Sutton family friend Billy Ray Taylor was fetching water from the backyard well when he saw a silvery object, “real bright, with an exhaust all the colors of the rainbow.” As he later recounted, it came silently toward the house, passed over it, stopped in the air—and then dropped straight to the ground.

Taylor, 21, and his 18-year-old wife had come from Pennsylvania to visit Lucky Sutton, with whom he had worked on a traveling carnival. The Suttons—50-year-old widow and matriarch Glennie Lankford, her two older sons and their wives, a brother-in-law and the widow’s three younger children (12, 10, and 7)—didn’t take Billy Ray seriously, laughing off his UFO account.

An hour later, alerted by the dog’s incessant barking. Lucky and Billy Ray went to the back door and made out a strange glow, in the midst of which they spied a small humanoid creature. About three-and-a-half feet tall, it had an “oversized head…almost perfectly round, [its] arms extended almost to the ground, [its] hands had talons…and [its oversized] eyes glowed with a yellowish light.” The body gave off an eerie shimmer in the light of the night’s new moon, they said—as if made of “silver metal.”

Terrified, the two men grabbed a 20-gauge shotgun and a .22 rifle and fired at the “little man”—its “hands” now raised as if held up at gunpoint as it came toward the back door. They reported that it then did a “flip,” scrambled upright and fled into the darkness.

Shortly after, the men saw a similar creature appear in a side window—and fired through the window screen. Still impervious to bullets, the “little man” again flipped, then disappeared. “I went out in the hallway and crouched down next to Billy, when I saw one approaching the door,” Mrs. Lankford told Isabel Davis, author of an extensive report called Close Encounter at Kelly and Others of 1955. “It looked like a five-gallon gasoline can with a head on top and small legs. It was a shimmering bright metal like on my refrigerator.”

READ MORE: Meet J. Allen Hynek, the Astronomer Who First Classified UFO 'Close Encounters.'

Touched by an alien?

Image from J. Allen Hynek Center for UFO Studies

The drama escalated when Taylor stepped outside under the small overhanging roof, and those behind him saw a claw-like hand reach down and touch his hair. The group screamed and pulled Taylor back while Lucky shot above the overhang and then at another similar creature in a nearby tree. It floated to the ground and then scurried into the woods.

The Suttons moved inside and spent several hours listening for movements, hearing mostly occasional scratches on the roof. At 11 p.m., the whole group ran for the cars and high-tailed it to the Hopkinsville police station at top speed.

After the local police chief called for backup, his team was joined at the Sutton farm by state police, military police from nearby Fort Campbell and a photographer from the Kentucky New Era. There, investigators found shell casings from the gun shots, but no other evidence. Neither could they find proof of heavy drinking. According to the Sutton matriarch, “liquor was not allowed in the farmhouse.”

Once the police and others left, though, the creatures returned between 2:30 a.m. and daybreak. Mrs. Lankford said she saw one glowing repeatedly by her bedside window, its claw-like hand on the screen.

READ MORE: Interactive Map: UFO Sightings Taken Seriously by the U.S. Government

Curiosity seekers descend

Image from J. Allen Hynek Center for UFO Studies

In the following days, after radio stations and newspapers (including The New York Times) reported the incident, hundreds of curiosity seekers descended on the farm, often ridiculing the Suttons as ignorant or fraudulent. When “No Trespassing” signs proved useless at discouraging them, the family tried charging admission: 50 cents for entering the grounds, $1 for information, $10 for taking pictures. After that, skeptics blasted them as fortune-seeking fabulists.

As the Kelly story spread into the world, it took on a life of its own. The number of “little men” grew to a dozen or more. A few years later, the little metallic men were conflated with an Eastern Kentucky woman’s report of a flying saucer and a six-foot tall man in green, helping launch the myth of little green men.

READ MORE: In 1952, the Flatwoods Monster Terrified 6 Kids, a Mom, a Dog—and the Nation

What investigators say

Glennie Lankford's firsthand account of the encounter reported in the Project Blue Book case file. USAF

The day after the incident, police investigators returned to the farmhouse, searching for evidence of a saucer landing, footprints, blood trails or scratch marks on the roof. They found nothing. Bud Ledwith, a local radio station employee, interviewed the adult eyewitnesses and made drawings based on their accounts. According to Davis, he was impressed by their remarkable specificity and consistency, even though the men were away from the farmhouse all day, unable to coordinate with the others.

While the incident eventually attracted the attention of the Air Force UFO-investigation program Project Blue Book, documents suggest that its team never officially pursued the matter—beyond checking in with their Fort Campbell counterparts who had been briefly at the scene the first night.

One of the most thorough investigations of the Kelly incident was undertaken in 1956 by ufologist Isabel Davis—and published several decades later by the Center for UFO Studies, a group founded by astronomer Dr. J. Allen Hynek, Project Blue Book’s civilian investigator. Her nearly 200-page report, co-written with Ted Bloecher, includes detailed maps, drawings, documentary records, summaries of similar accounts around the world and interviews with several Sutton family members and police investigators.

Davis summarized the latter's concern about the lack of physical evidence. But to her reckoning, none of the possible explanations—a deliberate hoax, a publicity play, group hallucinations—made sense. While questions arose about whether the young men were exaggerating (possibly fueled by hidden stores of liquor), Davis’s strong impression after meeting Mrs. Lankford was one of a somber, no-nonsense matriarch who abhorred the limelight and had no reason to lie. None of the witnesses, Davis noted, had any history of making “preposterous allegations.”

In 2006, Joe Nickell, senior research fellow of the international Committee for Skeptical Inquiry and a self-styled paranormal investigator, reviewed the accumulated evidence in an article entitled “Siege of the ‘Little Green Men’: The 1955 Kelly, Kentucky Incident.” In it, he raised suspicion about what he called Billy Taylor’s “embroidered testimony.” He matched Taylor’s UFO sighting with similar reports from that day, which suggested a small meteor in the vicinity.

As for the “little men,” Nickell floated an explanation used for other alien encounter stories: owls. In particular, the Great Horned Owl (a.k.a. the “hoot” owl) has long wings that could be mistaken for arms—along with talons, yellow eyes, long ears and round head that might also match the “little men” description. As for their metallic shine, Nickell suggests, they could have easily been reflecting moonlight.

But while hoot owls are known to be active at dusk and extremely aggressive when defending their nest, some investigators question characterizations of the creatures as hostile. To some, their behavior that night in Kelly appeared to simply be...curious.

WATCH: Full episodes of Project Blue Book online now.