232: Are there rainbows on other planets?

In this episode of Spacepod, host Carrie Nugent tackles a delightful question from three-year-old Maeve: 'Are there rainbows on other planets?' The answer, as explored with planetary scientist Dr. Alejandro Soto, is a nuanced 'maybe.' While Earth's rainbows rely on specific conditions—visible sunlight, liquid water droplets of the right size, and clear atmospheric skies—other planets and moons in our solar system fall short. Mars lacks liquid raindrops and has a dusty atmosphere, while Titan, though it experiences methane rain, suffers from low sunlight and thick atmospheric haze that would obscure any rainbow. The most promising candidates may be exoplanets—planets beyond our solar system—where Earth-like conditions could theoretically produce rainbows. The discussion also ventures into speculative territory: what would rainbows look like to alien eyes? Could they see infrared or ultraviolet rainbows, or perceive colors entirely different from our own? The episode closes with a reflection on how rare and special Earth's conditions are, and a call for kids to submit their own space questions for future episodes.