NASA has a habit of sharing raw images directly from spacecraft orbiting and rovers on the surface of Mars. The Red Planet is a vastly different environment from Earth, and people naturally look for some of the same phenomena in the atmosphere on Mars as we see here on Earth. One example is an image that NASA recently shared from the Mars Perseverance Rear Left Hazard Avoidance Camera known as Hazcam.
Running across the top left of the image, seen below, you can make out what appears to be a rainbow in the sky above the surface of Mars. However, looks can be deceiving. NASA’s Perseverance Mars Rover official Twitter page has shared the image, noting that many people who have seen it have asked if it was a rainbow.
The Perseverance team explains that it’s not a rainbow because rainbows aren’t possible on the Red Planet. A rainbow is created when light reflects off of round water droplets in the atmosphere of Earth. However, on Mars, there isn’t enough water to condense, and the planet is too cold for liquid water in the atmosphere.
The much less exciting explanation for what is seen in the image is a lens flare. A lens flare is a phenomenon where light is scattered or flared in a lens system, typically in response to a bright light resulting in an undesirable artifact within the image. In this instance, the lens flare looks very much like a rainbow.
Perseverance Rover has been on the surface of Mars for several months now and is currently conducting its science investigations in an attempt to find evidence of past life on Mars. The rover also recently placed the Ingenuity helicopter on the surface of Mars in preparation for its flight in the coming days.