Planets orbiting a binary pair of stars continue to be discovered by astronomers. Earth-like planets that could host liquid water, and perhaps life, may be just as likely to occur in a binary system as a single star system.

The two stars in the binary pair orbit around each other, while the planet orbits them both. This leads to a situation where the amount of radiation from each star changes by a small amount as the planet moves, causing an increase and then decrease in the starlight received with time. If this effect is too extreme, then it could potentially prevent such planets from maintaining liquid water on their surfaces.

My co-authors and I address this problem in a paper entitled “Constraining the magnitude of climate extremes from time-varying instellation on a circumbinary planet” and published in Journal of Geophysical Research – Planets. We use a simple climate model to calculate the maximum temperature that could be expected for the most extreme, but physically possible, case of a planet orbiting a binary pair. Even in the most extreme cases, we find that such a planet would be able to support liquid water in at least some parts of its surface.

Rather than sterilize the planet, the temperature variation from a binary pair acts more like a driver of seasons. Planets orbiting a binary pair may therefore experience unique seasons and weather patterns, but these would not be strong enough to make life impossible.