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Ottowell's Moon

Many of you were aware of (and even witnessed) the unusually-large full moon late last month - a triple-combination super, blue, blood moon, made possible by the coincidence of the second full moon of the month, at perigee and eclipsed by the Earth’s shadow. This interesting combination is beautifully illustrated in the Moon Section of Guy Ottowell’s Astronomical Calendar 2018.

Guy is renowned for his unique annual calendar and the striking illustrations contained therein. While he ended production of the annual hardcopy calendar in 2016, he has continued to generate and publish a reduced calendar in electronic form for his many worldwide fans.

In particular this year, you’ll find an interesting graph showing the earth-moon distance as it cycles over the course of the year. Looking at it, you’ll quickly see why the moon appeared so large twice in January and that the next super moon won't occur until December. You’ll also see that, while the moon will be just as close to us in July and August, it will be in its new phase, so not visible to us. A super moon requires the coincidence of close approach and full phase.

Besides the graphics, Guy provides interesting tidbits of information, including an explanation of why there will be no full moon at all in February and, again, two full ones in March. If you have any curiosity about the machinery of the heavens and enjoy fresh visualizations of it, I highly recommend Guy's calendar and his website generally!