A spooky blue moon will greet moongazers on Halloween Saturday after a full moon on the first day of this month, which was also the Mid-Autumn Festival.
Those expecting an azure night will be disappointed - a blue moon refers to two full moons appearing in the same Western calendar month.
The Space Museum said the next blue moon will appear again in three years on August 31, 2023. If you want a "spooky blue moon," you might have to wait for 19 years for the next blue moon to appear on Halloween.
The sky is forecast to be free of clouds on Saturday so no special astronomical equipment will be needed to appreciate an astronomical event that is once in a blue moon.