Photo of the Day

Grand Prismatic Spring, Yellowstone

Friday 2 October 2026

Aerial view of a vast hot spring: steaming deep-blue water ringed by yellow and bright orange bands that streak out across brown ground, a boardwalk beside it — Aerial photograph · July 2001

The largest hot spring in the United States, seen from the air. The deep blue center is too hot for almost anything to live in; the rings of orange, yellow and green around it are mats of heat-loving microbes, each kind settled at the temperature it likes as the water cools toward the edge.

Fun facts

The blue is the water itself. Water absorbs red light, so a deep, clear pool looks blue, for the same reason the open ocean does. source ↗
The colors shift with the seasons, since the microbes make more orange pigment in strong summer sun. source ↗
An enzyme from a microbe found in a nearby Yellowstone spring in the 1960s made PCR possible, the technique behind modern DNA testing. source ↗
Steam rising off the spring often tints blue-green from the light bouncing off the pool below. source ↗

Image: Jim Peaco / National Park Service
Licence: Public domain
Source: Wikimedia Commons