Sometimes there is a season with not three but four full moons. This is also the case this summer. The third of those three full moons is then called the Blue Moon.  In 2024, this will be the case on 19 August. A special event. That is why the term: Once in a blue moon is also used to indicate that an event is quite rare. Rineke made a beautiful Blue moon, high in the sky on a crystal clear glass stand of 30 cm high! Special, because you look right through it and still can’t see where the fourth quarter of that full moon is!