Thousands of people at a protest in Sao Paulo, Brazil, Tuesday spotted a mysterious bright light dart and zig-zag across the sky.
A video (above) posted on YouTube the next day shows the small glowing ball moving quickly through the clouds. Onlookers pointed and shouted, excited that what they were looking at was a UFO.
But it wasn't unidentified for long. Another video, also posted on YouTube (below) shows video footage from the flying object's perspective.
That mysterious thing in the sky was a drone with a camera attached, piloted remotely by Sao Paulo news station Folha TV.
Experts in the UFO field -- skeptics and extraterrestrial seekers alike -- agree that sightings are going to skyrocket as drone technology becomes cheaper and more accessible. That isn't necessarily a problem, but many people see any unexplained object in the sky as extraterrestrial, which can lead to fear and general hysteria.
"The whole business of UFOs is sold under the faulty logic of ignorance. We don't know what it was, therefore we know what it was," Joe Nickell, an investigator with Skeptical Inquirer, told The Huffington Post. "If you put anything up in the sky it will end up a UFO to many people."
"We don't call in planes or weather balloons as UFOs anymore, but drones are small, peculiar aircraft," Nickell said. "They're unfamiliar."
Nobody knows that better than Marc D'Antonio. He's a builder of custom models. Along with National Geographic, he constructed a working flying saucer to show just how easy it is to convince a town that there are ETs looming overhead. He flew the drone -- complete with green and blue lights -- over a small town in Connecticut in the winter, drawing reactions of fear, confusion and awe.
D'Antonio, who also works as the lead video analyst for the Mutual UFO Network, says that tests like these often spark an influx of UFO sightings. His experiment was educational and he revealed himself afterward, but he says some people will fly drones disguised as spacecraft just for laughs.
"[My project] showed I could walk into any hobby shop and in just 24 to 48 hours produce a craft," he said. "As drones become more prevelent, we're gonna see a massive surge of UFO sightings. Already, five percent are probably drone-related. Drones themselves are going to be taking center stage for a great deal of time."
Indeed, in 2011, a crowd of 25,000 protesters in Moscow watched a quad-rotor UFO hover overhead throughout the day. The sight caused mass confusion, OpenMinds TV reported at the time, but it was later revealed to be a local TV station's drone.
There are already FAA regulations in place restricting the altitude at which homemade drones can fly. Commercial and military drones, however, have few restrictions, D'Antonio said. To the untrained eye, any of these aircraft could be easily mistaken as a UFO.
"Many can fly out of sight -- but if they don't, they look weird," he said. "It's easy see drones as otherworldly."
Also on HuffPost:
Melbourne, Australia, Feb. 2013
This is a composite image of how three alleged UFOs maneuvered about in the sky over Melbourne, Australia, in early February, 2013. The final verdict isn't in yet on whether they're birds, aircraft, balloons, bugs or something truly unidentified.
These candle-lit Chinese lanterns can rise high into the sky and are often mistaken for UFOs.
Exploding Weather Balloons, Not UFOs
On Dec. 20, 2012, a bright, circular object (pictured at the top of this composite image) was videotaped exploding in the skies above Sacramento, Calif. It wasn't immediately identified, resulting in speculation that it was either an alien spacecraft, military top secret weapon, runaway planet, North Korean satellite, among others. Within a short period of time, it became apparent that this was a weather balloon. The bottom part of this image shows such a balloon as it ascended over Tampa Bay, Fla., on July 2, 2012, and exploded in an identical manner as the Sacramento object, probably much to the dismay of all true ET believers out there.
Boomerang UFO composite images -- 10-5-12
This is a composite of images shot by two eyewitnesses of a boomerang-shaped UFO they reported seeing over their Burbank, Calif., home on Oct. 5, 2012. Mutual UFO Network photo/video analyst Marc Dantonio concluded the object was likely "a balloon, floating on the wind that has collapsed in half."
Changing UFO Pattern -- Warren, Mich. 1-10-13
This four-image series of lights in the sky was recorded over Warren, Mich., on Jan. 10, 2013. The lights were seen changing into several patterns. The most logical explanation for these types of UFOs is a series of balloons or lanterns.
UFOs Over Earth
This composite image shows four different times that alleged UFO were photographed above Earth by either space shuttles or the International Space Station. The big question is whether or not they are truly unidentified objects or if they are more likely reflections from spacecraft windows, meteors or fast-moving spacecraft-generated debris.
Pink UFOs Or Lens Flares?
What appear to be pink-red UFOs are actually lens flares from the Google Earth street view camera as it snapped images in Texas (left) and New Mexico (right).
Lens flares Arizona
These two flying saucer-shaped, pink-colored lens flares were created by the Google Maps camera as it drove through locations in Sedona, Ariz. (left) and Flagstaff, Ariz. (right). The images were snapped in April 2009. Submitted to HuffPost by trenna.
Lens flare Whiteriver, Ariz.
This skybound lens flare was created by a Google Maps camera in June 2008 over Whiteriver, Ariz. Submitted to Huffington Post by Cheryl Weeks.
Lens flare Gulfport, Miss.
This very Earthbound lens flare was created by a Google Maps camera in November 2007 at Gulfport, Miss. Submitted to Huffington Post by Jenni Parker.
Lens flare Eureka Springs, Ark.
This seemingly grounded lens flare was created by a Google Maps camera in January 2008 at Eureka Springs, Ark. Submitted to Huffington Post by SE.
Lens flare Escanaba, Mich.
This lens flare appears to be following a car. The Google Maps image was created in October 2008 at Escanaba, Mich. Submitted to Huffington Post by Mary Robinson.
Cincinnati Skydivers NOT UFOs Sept. 28, 2012
On the night of Sept. 28, 2012, a group of strange-looking lights appeared in the sky near Cincinnati, Ohio. First there was one, then, two, then three lights, slowly descending. It turns out, however, that these lights were originating from a group of skydivers performing a pyrotechnics jump at the La Salle High School homecoming event.
Some UFO sightings may be due to a natural phenomenon known as sprites, like this one shown from 2006. "Lightning from [a] thunderstorm excites the electric field above, producing a flash of light called a sprite," said geophysicist Colin Price.
Clouds: Saucer-shaped or "lenticular" clouds that form at high altitudes have been confused with UFOs.
Blimps or Advertising Balloons
Blimps or advertising balloons: These can look like flying saucers from some angles, especially at night.
Sunken Ship in the Baltic Sea
On June 19th the Swedish-based diving company Ocean Explorer discovered something they've never quite seen before. They were exploring in the Baltic Sea between Sweden and Finland looking for sunken treasures when a very unusual image suddenly appeared on the sonar. A 197 feet diameter cylinder shaped object was discovered at the depth of approximately 275 feet which resembles the Millennium Falcon from the movie Star Wars.
Baltic Sea UFO 1
An image released on June 15, 2012, shows a close-up view of the unidentified object sitting on the bottom of the Baltic Sea.
Baltic Sea UFO 2
Close-up of rock bed that forms the Baltic Sea UFO, which still mystifies researchers.
Baltic Sea UFO 3
One of several odd stone circle formations, sitting on top of the unidentified object at the bottom of the Baltic Sea.
Antarctic UFO -- Aug. 10, 2012
A circular UFO hovers above the Neumayer-Station III research facility in Antarctica on Aug. 10, 2012. Theories ranging from a simple weather balloon to a more elaborate ship from another planet have run the Internet gamut. The next slide shows a closeup of the object.
Antarctic UFO Closeup -- Aug. 10, 2012
This is a closeup of the UFO from the previous slide. No official explanation has been offered about the object.
Manufactured UFO -- 2011
Pictured is a quad copter -- a deliberately manufactured UFO created by special effects wizard Marc Dantonio for a National Geographic special, "The Truth Behind: UFOs," which aired in December 2011. On the left is what the small device looks like resting on the ground, measuring 4 feet in circumference. At right, is how it appeared behind a tree in the night sky.
Police Dashboard Camera In Texas
In February of 2012, this fireball was captured by a Texas police chief's A dashboard camera. F.A.A. say this was probably a meteor, falling to Earth. .
Meteors: Space debris can create a spectacular light show when it burns through the Earth's atmosphere, and sometimes reported as UFOs.
Civilian or Military Aircraft
Civilian or military aircraft: Planes can look mysterious at night or in certain light conditions, thus confusing an observer.