"It was clear and certainly not a bug," Henry told local ABC TV affiliate News 10.
Henry claims what she saw was not from this world and that she was scared to have witnessed such an anomaly.
"I was like what was it doing there," she said. "Why was it there? What was it doing? And I said, the next time I come here, the barn will be beamed up."
According to Elaine Murphy, the president of the Santee Historical Society, paranormal things happen all the time at the historical barn turned museum.
"We think someone's come into the barn and we get up to look, and no one is there," she said.
A group of people who oversee the museum told News 10 that the barn used to be part of a poor farm and hospital grounds and that multiple ghost sightings have been reported at the museum.
Henry, who uploaded a video of her findings on YouTube, wrote in the description that even though "paranormal activities" take place around the museum all the time, this was "the first time a UFO has made a visit."