File photo: The moon rises over the Nairobi National Park. (Reuters)
In a delight for skywatchers, the second full moon of July made its appearance on Friday evening. The rare phenomenon - the sighting of second full moon - is referred to as Blue Moon.
The first full moon of the month had appeared on July 2. Usually, in a calendar year, only one full moon is visible every month.
In addition to those 12 full lunar cycles, each calendar year contains an excess of roughly 11 days due to the difference between lunar and solar years. These extra days accumulate, and every two or three years, there is an extra full moon.
The last time the event occurred in August 2012. The next time it will occur in January 2018.