Story at a glance
- NASA’s Perseverance rover captured an image of what looks like a rainbow on Mars.
- Users on Reddit have been debating the source of the rainbow.
- Scientific studies of Mars’s atmosphere says a rainbow shouldn’t be able to form on the dry planet.
A recent image taken by NASA's Perseverance rover appeared to show a breathtaking rainbow on Mars. The photograph has caused mass speculation online, as scientific evidence shows there shouldn't be rainbows on Mars.
On Earth, rainbows appear when sunlight meets the right atmospheric conditions, in which the light hits and reflects off of individual water droplets in the atmosphere.
However, given the cold, thin, and dry atmosphere of Mars, the chances of the image being of an actual rainbow were unlikely.
Reddit users speculated that it could be a "dustbow," with the reflections being caused by dust rather than water droplets.
Further speculation on the site has come from a 2015 "Ask Me Anything" with NASA team members in which NASA Mars Program Office Chief Scientist Rich Zurek said it was possible that "icebows" could appear on Mars, because while there are no water droplets, snow has been observed at the Poles.
However, the most supported theory appeared to be that the "rainbow" was caused by an artifact causing random rays of light entering and randomly dispersing inside the lens, similar to a "lens flare" in your typical camera.
This was supported by Dave Lavery, the program executive for Solar System Exploration at NASA, who told Forbes, "Definitely not a rainbow. ... It is just internal reflections in the camera lens."
"The rover is almost due north of the helicopter, so the camera is looking almost straight south at about 2:00 p.m. local Mars solar time when these images were taken," he said, adding that those are the prime conditions for stray light to interfere with a camera's optics.
NASA finally gave people the answer they were looking for, taking to NASA's Perseverance Mars Rover's Twitter on Tuesday night. "Many have asked: Is that a rainbow on Mars? No. Rainbows aren't possible here. Rainbows are created by light reflected off of round water droplets, but there isn't enough water here to condense, and it's too cold for liquid water in the atmosphere. This arc is a lens flare," the tweet said.
Whatever the cause, it sure is beautiful.
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