Summary:
- A "black moon" is a rare astronomical event where there are two new moons in the same calendar month, making the second new moon appear black in the sky.
- The next black moon will occur on August 23, 2025, when the new moon will rise with the sun, making it difficult to observe.
- Black moons are not as rare as a "blue moon" (two full moons in the same calendar month), but they still only happen once every 32 months on average, making them a unique celestial event to witness.