Are there rainbows on Mars? NASA decided to answer this questions in the latest episode of its ‘Ask The Expert’ series. Shared on Instagram, the video features the US space agency’s planetary scientist and Mars expert Mark Lemmon.
The answer is “no.” But several other conditions on Mars are similar to Earth. Lemmon explained that the formation of a rainbow requires more than just water. Rainbows are formed when sunlight passes through a spherical droplet, reflects off the back and comes towards the human eye, usually after rainfall.
Lemmon said for rainbows to form, water droplets are needed as they are spherical. On Mars, there are not adequate water droplets. The scientist said tiny droplets available on Mars are 20 times smaller than human hair and 10 times smaller than the droplets found in Earth’s clouds. The droplets have to be at least 10 times bigger to create a rainbow, said Lemmon, adding that even though snow could be found in Martian clouds, it is of no use to form rainbows.
So, what was that the Perseverance rover saw arcing across the dusty Martian sky in early April? After a lot of speculation on social media, NASA dismissed the idea, saying that the arc was a lens flare. NASA also said that there isn’t enough water on Mars to condense and it’s too cold for liquid water in the atmosphere to take the shape of spherical water droplets.
Lemmon, too, referred to this incident in the video. While there are no rainbows on Mars, there are many Earth-like phenomena on the red planet, including clouds, storms, and winds.