A leader of NASA's Mars Curiosity rover team has offered a couple of explanations for an anomalous bright spot that showed up on pictures from the Red Planet but they're not the conventional explanations.

Let's get this straight first: It's not an alien spotlight, according to Justin Maki, an imaging scientist at NASA's Jet Propulsion Laboratory who is the lead for Curiosity's engineering cameras. Maki isn't giving any weight to the not-completely-serious claims that are being bandied about by UFO websites.

At the same time, Maki isn't immediately dismissing the phenomenon as a double-shot of cosmic rays or data dropouts. In his view, that spot of light could have entered Curiosity's right-hand navigation camera, even though there's no sign of the spot in the stereo imagery from the left-hand camera.

Maki and his colleagues think it could be a well-placed flash of reflected sunlight, or light shining through a chink in Curiosity's camera housing. Here's his explanation, passed along via email:

"Bright spots appear in single images taken by the Navigation Camera on NASA's Curiosity Mars rover on April 2 and April 3. Each is in an image taken by this stereo camera's right-eye camera [with links to the April 3 and April 2 pictures] but not in images taken within a second of each of those by the left-eye camera [again, with links to April 3 and April 2]. In the two right-eye images, the spot is in different locations of the image frame and, in both cases, at the ground surface level in front of a crater rim on the horizon.

"One possibility is that the light is the glint from a rock surface reflecting the sun. When these images were taken each day, the sun was in the same direction as the bright spot, west-northwest from the rover, and relatively low in the sky. The rover science team is also looking at the possibility that the bright spots could be sunlight reaching the camera's CCD directly through a vent hole in the camera housing, which has happened previously on other cameras on Curiosity and other Mars rovers when the geometry of the incoming sunlight relative to the camera is precisely aligned.

"We think it's either a vent-hole light leak or a glinty rock."

NASA spokesman Guy Webster told NBC News that both pictures were taken during the Martian afternoon. He said a member of the rover team is checking for other examples of light leaks and Martian sunglint.

Even if the flash is the glint from a shiny rock, the crater's rim looks far enough away that Curiosity's course is unlikely to be changed to investigate. Unless, of course, it turns out to be a Martian flashing a mirror.

A bright spot shows up in Curiosity's right-hand navigation camera image from April 2.

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NASA Explains Martian Flash, and It's Not What You Think