NASA scientists have tried to explain a mysterious white light captured in a photograph of the surface of Mars.

The space agency published a black-and-white picture taken by the Curiosity rover on June 16, which shows a bright spot on a distant hill. Photos taken immediately before and after show no bright flash.

A NASA spokesperson told Fox News the anomaly is "likely an effect of the Sun" and "images with effects like this" are seen "pretty routinely."

Another NASA spokesperson told the light may have resulted from sunlight reflecting off of the rover's sensors.

“The rover science team is also looking at the possibility that the bright spots could be caused by cosmic rays striking the camera's detector,” the spokesperson said.

Curiosity has been sending photos back to Earth since it landed on Mars in August 2012.

The image has sparked online conspiracy theorists to claim the spot is evidence of alien life.

Website claims the object “appears to be floating above the surface of Mars.”

“It’s clearly keeping a safe distance from the Curiosity rover, however I imagine it didn't plan on the rover having cameras going in front and behind it,” Scott C Waring wrote on the site.

“This object has a hump on its upper center and a smaller hump or dome on its lower center...much like a classic UFO. Life...finds you.”

Meanwhile, the rover has recorded the largest spike in methane gas on the planet’s surface since its mission began.

NASA scientists have studied the gas readings detected June 19, and found levels have decreased sharply to normal background levels.

Methane is usually produced by living things on Earth, but NASA confirmed it can also be made by the interaction of rocks and water on the Red Planet.

Curiosity doesn't have instruments that can definitively say whether the source of the methane is biological or geological, NASA confirmed.

"The methane mystery continues," said Ashwin Vasavada, Curiosity's project scientist at NASA's jet propulsion laboratory in Pasadena, California.

"We're more motivated than ever to keep measuring and put our brains together to figure out how methane behaves in the Martian atmosphere."

Scientists first reported methane on Mars more than decade and a half ago.

“While increased methane levels measured by @MarsCuriosity are exciting, as possible indicators for life, it’s important to remember this is an early science result,” Thomas Zurbuchen, associate administrator at NASA’s science mission directorate, tweeted.