We Asked a NASA Scientist: Are There Rainbows on Mars [Video]

Are there rainbows on Mars? Sadly no. But there are a whole lot of other conditions on Mars that we have right here on Earth! NASA scientist Mark Lemmon explains why the Red Planet is a rainbowless world.

That’s a great question. There are water clouds in the thin atmosphere of Mars, so why not rainbows? You may have even seen an image from the Perseverance rover with an arc across the sky. That was not a rainbow; it was a lens flare. We saw that lens flare even in brightly lit laboratory images.

Rainbows, as it turns out, need more than just water, the substance. In a rainbow, sunlight enters a spherical droplet, reflects off the back, and comes back toward you. Unlike ice, liquid water droplets are made into spheres by the water’s surface tension — it pulls itself together. Snow does not make rainbows because it has a complex shape. Martian clouds are far below freezing. You do not get liquid droplets that can make rainbows; there’s just not enough water.

The droplets are 20 times smaller across than a human hair, 10 times smaller than Earth’s cloud droplets, and far smaller than rain. They would have to be more than 10 times bigger to make a rainbow with a thousand times more water.

While there aren’t rainbows on Mars, there are many Earth-like weather phenomena. There are still clouds on Mars when the season is right, both water ice as we have on Earth and clouds of dry ice carbon dioxide. And there are dust devils, dust storms, and winds that blow the clouds and dust around. So, weather is still a big part of what the rovers are looking at on Mars. But I’m sorry to disappoint you. Mars has some Earth-like weather, but no rainbows.

We Asked a NASA Expert Video Series

• Why is Venus Called Earth’s Evil Twin?
• Is NASA Really Crashing a Spacecraft Into an Asteroid?
• Is NASA Aware of Any Earth-Threatening Asteroids?
• When Was the Last Time an Asteroid Hit Earth?
• How Did Perseverance Mars Rover Pick Its Landing Spot?
• What if an Asteroid Was Going To Hit Earth?
• Did Mars Ever Look Like Earth?
• What Are Lagrange Points?
• What Are the Trojan Asteroids?
• Is There Oxygen on Mars?
• Does NASA Know About All the Asteroids?
• Do Aliens Exist?
• Is There Weather on Mars?
• Will an Asteroid Ever Hit Earth?
• Is Mars Habitable?
• Could Microbes Survive a Trip to Mars?

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