A new photo snapped by NASA’s intrepid Curiosity rover appears to have captured a mysterious glow on Mars.
The photo, which seems to show a light floating above the planet’s surface, was taken on June 16, or Sol 2438, of Curiosity’s mission to explore the Red Planet. Martian days are known as Sols and last for 24 hours, 39 minutes and 35 seconds, meaning a year – or one orbit around the Sun – is 668 Sols (or 687 days).
Suffice to say, it is probably not an indication of alien life, although NASA will happily admit it’s an anomaly.
So, what is going on here?
Curiosity has been roaming the surface of Mars since 2012, sending back copious amounts of images (including selfies) for data scientists to wade through. The space probe has 17 cameras on it – the most of any NASA planetary mission – so that’s a lot of images, and some of those have featured anomalous lights too.
It could be as simple as a shiny rock catching and reflecting the Martian sunlight, or it could be cosmic rays. They’re both pretty common and have been spotted before. Occasionally, it's just lens flare from the camera.
Curiosity takes pictures using two Navcams that act as its left and right eyes. If it was light glinting off a particularly shiny rock, it would likely be snapped up by both cameras, although that isn’t always the case. In this instance, the photo was taken by the right Navcam, the left apparently preoccupied with attempting a selfie.
If you’re thinking it may have been a particularly clever alien spacecraft that knew how to avoid at least one camera, it would have had to be an incredibly speedy spacecraft too, as the raw data shows the images taken fractionally before and after the image was snapped, and neither shows the blob of light.
It’s more likely the bright spot is a cosmic ray, as according to NASA, they pop up in images Curiosity sends home each week.
"In the thousands of images we've received from Curiosity, we see ones with bright spots nearly every week," Justin Maki, leader of the team that built and operates Curiosity's Navcams, explained back in 2014 after another image made the headlines. "These can be caused by cosmic-ray hits or sunlight glinting from rock surfaces, as the most likely explanations."
Cosmic rays are charged particles that whizz around the cosmos and occasionally collide with things, like cameras. Because Mars' atmosphere is thinner than Earth’s, it doesn’t block as much cosmic radiation, so we are more likely to see them.
So, if this happens every week, why has the photo caused a bit of a stir? Because people really want it to be aliens.