Pic of the Day

Old Faithful Geyser. The epitomy of geysers in Yellowstone.

The time between eruptions has a bimodal distribution, with the mean interval being either 65 or 91 minutes, and is dependent on the length of the prior eruption. Within a margin of error of ±10 minutes, Old Faithful will erupt either 65 minutes after an eruption lasting less than 2 1/2 minutes, or 91 minutes after an eruption lasting more than 2 1/2 minutes.