New slant on blue sky research

Scientists from the National Physical Laboratory (NPL) have helped to identify the bluest sky in the world

When online travel agent Expedia launched a quest to identify the world’s bluest sky, NPL joined the hunt to ensure that results were accurate and evaluated against international measurement standards.

“Colour is something people take for granted, but it’s quite difficult to quantify. That’s where NPL comes in,” says NPL scientist Dr Nigel Fox. “International standards for describing colour exist because they are important to industry - from brewers to petrochemical plants.”

Expedia sent an explorer on a 64,000 mile quest to find the best holiday sky. NPL’s Optical Radiation team equipped them with the tools and support they needed to get accurate results from beaches and mountaintops around the world.

The challenge for the team was to adapt specialised lab techniques for a journey around the world. “We wanted to make sure the equipment would survive 72 days of hard travel, on and off 56 planes,” says Fox. “Wherever we could, we found lightweight, cheap substitutes for specialist lab equipment and it proved to be very robust. We are talking about only a 4% margin of error - a respectable result even for some commercial lab based measurements”

The top three bluest skies were found to be: 

1. Rio de Janeiro, Brazil
2. Bay of Islands, New Zealand
3. Ayers Rock, Australia