Solunar Theory Explained

Solunar activity is one of the inputs behind the Smart Bite Score. Here's where the idea comes from and how Simple Tides sources the underlying data.

Where it comes from

Solunar theory dates back to 1926, when outdoorsman John Alden Knight published the first "Solunar Tables," proposing that fish and game are more active during specific positions of the sun and moon relative to a given location. The tables have been refined over the decades but the core idea hasn't changed much.

Major and minor periods

The theory identifies two major periods each day, roughly when the moon is directly overhead or directly underfoot (on the opposite side of the earth), each lasting a couple of hours. It also identifies two shorter minor periods, tied to moonrise and moonset. Activity is expected to pick up around these windows.

Moon phase and illumination

Full and new moons are traditionally considered the strongest solunar days, since that's when the sun and moon's gravitational pull align most directly. Simple Tides shows moon phase and percent illumination alongside solunar activity so you can see both at once.

Does the science hold up?

Formal research on solunar theory is mixed: some studies find a modest correlation between lunar periods and animal activity, others find no significant effect once other variables like tide and weather are controlled for. It remains genuinely popular among experienced anglers and hunters as one signal among several, which is why Simple Tides includes it as an input rather than treating it as a standalone forecast.

How Simple Tides sources this

Moon phase, illumination, and rise/set data come from the FarmSense API; sunrise and sunset come from Sunrise-Sunset.org. Simple Tides combines these with your selected station's tide data to produce the solunar activity read shown for each location.

See how this feeds into the overall rating in our Smart Bite Score guide.