THE MOST COLOURFUL SIGHTS ON EARTH

Long-distance travel is lovely, but it saves a bit of cash if we bring some of the planet's most spectacular natural places to you

- DR HELEN PILCHER

SPRING TO LIFE

GRAND PRISMATIC SPRING, YELLOWSTONE NATIONAL PARK, WYOMING, US

Yellowstone's Grand Prismatic Spring is the largest hot spring in the US, and it boasts a veritable rainbow of colours. Hot water bubbles up through a crack in the Earth's crust, supplying the spring. Very little can survive in the centre of the spring, where temperatures can reach nearly 90°C, so the water here is a pure blue. But away from the centre, colourful, heat-loving bacteria begin to thrive, and the spring's concentric rings of temperature create different niches. The colours come from the photosynthetic pigments, such as chlorophyll and carotenoids, that the bacteria use to manufacture energy from sunlight. Carotenoid-rich Synechococcus bacteria are responsible for the innermost yellow ring, while slightly further from the centre, Synechococcus rubs shoulders with other carotenoid-containing bacteria, giving more of a tangerine colour. Closer to land, where the bacteria are more diverse still, the cocktail of pigments creates a rusty Martian hue.

A SLICE OF RAINBOW CAKE

ZHANGYE NATIONAL GEOPARK, CHINA