The Halloween Moonrise picnic will be Wednesday, October 31 from 6 pm - 9 pm. Moonrise will be around 6:30 pm. The official full moon is two days (and one hour) earlier, but we'll get an even better view of craters and shadows on the moon, perfect for Halloween.
Richly colored autumn leaves are starting to fall; deer are fattened up for winter. Fields have been harvested leaving them bare for fox and hare to glean the ground for leftover grain. It is time to hunt. At least according to American Indians who called October's Full Moon the Hunter's Moon. Captain Bob calls it the All Hallows Eve Moon.
WHEN: Wed 31 October 6 - 9 pm Moonrise will be about 6:30 pm. .
WHERE: Pont des Arts. We'll gather around a bench towards the Left Bank side of the bridge. Nearest metros: Pont Neuf and Louvre-Rivoli.
WHAT: Everyone brings food and drink to share. Hot drinks will make you especially popular: Hot cider, hot chocolate, spiced wine, tea, coffee, etc.
WHY: Share one of the most memorable sights in Paris with some of the nicest people around.
WHO: You and your friends.
HOW to find us: Keep your eyes out for a small white telescope on tripod if the sky is clear. Check in by cell phone if you can't find us: 0614 17 37 97.
THEME: Halloween. Costumes. I'll bring the jack-o-lanterns. Nuff said.
PUZZLER: How often does a Full Moon fall on Halloween? How often does a Blue Moon fall on Halloween?
PUZZLER ALERT: Some people have complained that I shouldn't give the Puzzler Answer in the same email as the Puzzler Question. Here's why I do it:
1) I forget the answer by the next month.
2) Everybody else forgets the question by the next month.
3) Only one or two people send in their answers.
So here's a solution:
1) If you don't want your challenge spoiled, don't read the Puzzler Answer (below),
before you think about your own answer.
2) Send me your answers, comments and corrections anyway.
First to the Blue Moon question (using the popular, but not technically correct definition that a "Blue Moon" is the second full moon in the same month). It happens that every Full Moon on Halloween is a Blue Moon. Why? Because the average interval between full moons is 29.5 days so if there's a full moon on Oct 31 the previous one would also fall in October.
And using the same interval, my intuitive answer says the odds that Oct 31 is a Full Moon should average out to once every 29 or 30 years. However, this century a full moon falls on Halloween much more frequently - in 2001, 2020, 2039, 2058, 2077, 2096. That's once every 19 years - and not on average, but exactly. It turns out that, the 19-year Metonic cycle is an important factor, since it causes the dates of Full Moons to repeat at intervals of 19 years, or multiples of 19 years. This effect is especially evident in the 21st century, which has an unusually large number of Halloween Full Moons. And those are not just my words (as you can tell by the different font and the fact that I have no idea what Metonic means). For more info check out: http://www.obliquity.com/astro/halloween.html
Happily, that website confirms the original intuition. Over the last 6000 years there have been 3 to 4 Full Moon Halloweens per century on average. The 21st century just happens to offer extra opportunities for Howloween werewolves.
The website also shows that some cities have more Full Moon Halloweens than others. For example, San Francisco only had 3 of them last century, while London, New York and Chicago had 4. But San Francisco makes up for the deficiency by having 6 of them this century, while London and New York only have 5. You may think a Full Moon falls on the same day everywhere. But this isn't true and I'll leave it to you the think about why.
Ciao for niao,