Over the past few months -- between Aug. 1 and Oct. 15 -- more than 100 UFOs have been seen along the India-China border, and the sightings have officials puzzled.
The Times of India reported this week that "yellowish spheres appear to lift off from the horizon on the Chinese side and slowly traverse the sky for three to five hours before disappearing."
The Times of India added that the UFO sightings have stumped numerous Indian military groups, including their air force, NTRO technical intelligence agency and the Indo-Tibetan Border Police (as seen below).
Army officials in charge of the 2,100-mile border between the giant Asian countries have reportedly ruled out Chinese drones or low-orbit satellites, according to the Los Angeles Times.
Members of the Indian ITBP sent reports to their Delhi headquarters, describing the spheres as Unidentified Luminous Objects, or ULOs, whether they're seen during the day or night.
After examining hazy photographs of the ULOs taken by the ITBP, army officials ruled out unmanned aerial vehicles, reports India Today.
In September, the Indian army brought a mobile ground-based radar unit and spectrum analyser to the top of a mountain near Pangong Lake between India and China.
According to India Today, while one of the ULO's was spotted visually, it wasn't picked up on the radar, which indicated it was non-metallic.
Also in September, a team of astronomers from the Indian Astronomical Observatory at Hanle observed the ULOs for several days. While they couldn't figure out exactly what the objects were, they ruled out meteors and planets.
Two years ago, the Indian air force looked into UFO sightings, eventually explaining them as Chinese lanterns (see example of some Chinese lanterns above).
And there have been other reports of luminous objects reportedly seen on the Chinese side of the border, India Today reported.
Even though scientists aren't sure what these ULOs are, they're not ready to consider them visitors from another planet.
"There is no evidence of the UFOs being of extraterrestrial origin," India Today quotes astrophysicist Jayant Narlikar. "The implication of them being alien objects is fancy, not fact."
Here are some UFOs or ULOs that were easily explained.