Can rainbows form on Mars? NASA scientist explains why not

Though Mars has some similar weather features to Earth, factors at play make forming a rainbow impossible on the Red Planet.

A RAINBOW stretches over Kibbutz Misgav Am in the Upper Galilee (photo credit: JOHN T. HUDDY/THE MEDIA LINE)
A RAINBOW stretches over Kibbutz Misgav Am in the Upper Galilee
(photo credit: JOHN T. HUDDY/THE MEDIA LINE)

Rainbows are one of the most visually striking phenomena that can occur on Earth, holding places in cultures and mythologies around the world. Whether you believe it is God's reminder of His promise to never flood the Earth again or that it leads to a pot of gold or if you simply see it as a symbol of the LGBTQ+ community - not to mention the established scientific reasons behind it - chances are rainbows hold some form of meaning to everyone on Earth.

But what about on Mars? Is this spectrum of colors possible on the surface of the Red Planet?

According to NASA scientist Mark Lemmon, the answer is definitely no.

Why is this? After all, there are water clouds in the Martian atmosphere - though the atmosphere is incredibly thin and it doesn't mean it can rain by any means.

In fact, as noted by Lemmon in a video published by NASA, many people may have even seen a rainbow arc of sorts in the sky of Mars in pictures sent back by the Perseverance rover.

But this is not a rainbow. It is simply a lens flare.

But if rainbows are a weather phenomenon, could it not still be possible? It may not rain on Mars, but the Red Planet does have its own weather that can, at times, be similar to Earth. 

As noted by Lemmon, Mars can have clouds. They have dust storms where clouds and dust are blown by the wind. Clouds of water ice and dry ice carbon dioxide can sometimes be found in the atmosphere.

But contrary to what many people think, it takes more than just water to make a rainbow.

To put it simply, Mars is cold. The temperatures on the Red Planet are so low that their clouds are far below freezing. That is why it doesn't rain.

On Earth, snow and ice can't form rainbows - only rain can. 

Specifically, this is done when sunlight enters a spherical rain droplet, reflects off it, and comes back. But Mars doesn't have spherical droplets.


Spherical droplets are formed when liquid water is pulled together with surface tension. Snow can't do that because its shape is too complex.

Not only that, but Mars's droplets are very small, 10 times smaller than cloud droplets on Earth. If it wanted to form a rainbow, it would need to be 10 times bigger with a thousand times more water.