There’s been a lot happening on Mars lately.

Or really, there’s always been a lot happening on Mars. But it’s just now, thanks to NASA’s Curiosity rover traipsing around the distant red planet, that we’re able to get a glimpse of what it’s like atop one of the galaxy’s most intriguing places.

One of the strangest of those recent glimpses? A lone, glowing light, captured in just one photo among a series taken by Curiosity. The image immediately sparked interest among those trying to figure out whether Mars is home to a life form not seen on Earth. Why did the light appear in just one of the photos? What did it mean? Was it a message sent from the alien colony living on Mars, preparing their attack on Earth?

OK, so that last one was a little implausible ... but it was among the possible explanations some conspiracy theorists gave for the unusual glow.

Unfortunately for those theorists (but good for anyone hoping not to experience an alien takeover!), the answer was a little more mundane than they were likely hoping. NASA officials said that they’ve seen similar glows in photos before. They think it’s probably a glint of light from a reflection from the sun, or some kind of camera lens flare.

However boring the explanation for the mysterious light may be, it was far from the only thing that Curiosity uncovered recently. The rover found what may be a much more convincing sign of life on the planet: methane.

Methane is an odorless, colorless and flammable gas that, on our planet Earth, is produced both naturally and through human and animal activity. Naturally, it can be found in many life breeding grounds such as lakes and marshes. Livestock also produce vast amounts of methane, and human activity such as fracking, mining for coal and burning forests also produce methane.

Many biologists are worried about rising methane levels on Earth, since it’s a greenhouse gas. But on Mars, its presence could be an indicator of life.

Last week, the Curiosity rover found 21 parts per billion units by volume of methane. That was enough to surprise scientists and have them order more methane tests. During a second sniff around for methane, though, results were much lower. NASA representatives believe the earlier spike was thanks to a methane plume that came and went, begging more questions about the nature of the plume, where it came from and what it can tell us about potential life on Mars.

Unfortunately, we just don’t know yet. Curiosity doesn’t have the ability to detect where the methane came from, so scientists will have to keep searching for more clues from the data at hand.

And they’ll have a lot more data to work with starting in a few years, when the Mars 2020 rover will start scoping out the planet. The machine is slated to give us the best idea of what it’s like on Mars yet, as well as collect rock samples. Until then, Curiosity will keep digging, and the mystery of Martian life will live on.