Yesterday’s Super Blue Blood Moon was big news here at Caterpickles Central. Most of us staggered out of bed in time to see it. Even Canelo seemed pretty pleased about the fact that the moon turned Canelo-colored, if only for a little while. He kept his fur extra tufty all day, and was careful to be rolled up into a little moonball whenever I approached him. He even taunted a snow leopard on Twitter about it.
But while Canelo was busy allowing the Super Blue Blood Moon go to his head, my daughter’s brain was busy thinking about opposites.
As you know, a blue moon is the second full moon in any given month. My daughter wanted to know if the opposite ever happened.
“Are there ever two new moons in a month, Mommyo? And if so, what’s that called?”
In case, you like me, need a refresher on what a new moon is — it’s basically a night on which the moon’s Earth-facing side is completely in the Earth’s shadow, so it looks like there is no moon at all up there.
A new moon occurs every 29.5 days. This lunar calendar only imperfectly lines up with our months, which means every once in a while a calendar month will have two new moons in it.
When that happens, the second new moon is called a black moon. According to Space.com, black moons occur about every 32 months. The last black moon for those of us in the Western Hemisphere occurred on Friday, September 30, 2016. (Time zone differences meant that folks living in the Eastern Hemisphere had to wait until October 30 or October 31, 2016 for theirs.)
As this article in the Sun points out, the term black moon can also refer to a month in which there is no new moon at all. The only calendar month short enough to have this happen is February. Given yesterday’s Super Blue Blood Moon and a lunar calendar that requires 29.5 days to cycle, savvy readers will not be surprised to learn that this sort of black moon is expected to happen again this very month.
- Black Moon 2016: What it is and why you can’t see it (Space.com)
- What is a black moon, why do they happen, and when is the next one? (Sun)