Explainer |

How to see a blue moon in East Asian skies this weekend: when the phenomenon will occur, what to expect, and which places will have the best view

• Four full moons are visible in the same three-month astronomical season. The third is a blue moon, which appears in the sky underneath the planet Jupiter
• If skies are clear it can be a spectacular sight, and it will be 100 per cent illuminated when it appears over Hong Kong on August 22