With 8-Across, rare lunar phenomenon occuring on August 30th Crossword Clue

 The rare lunar phenomenon occurring on August 30th is a Super Blue Moon. This is a combination of two rare lunar events: a blue moon and a supermoon.

A blue moon is the second full moon in a calendar month. This happens about every 2.7 years.

A supermoon is a full moon that occurs when the moon is at its closest point to Earth in its orbit. This happens about every 14 full moons.

The Super Blue Moon on August 30th will be the closest full moon to Earth since January 2019. It will appear about 14% larger and 30% brighter than a regular full moon.

The next Super Blue Moon will not occur until August 2026.