The Full Sturgeon Moon!

Hey, hey, sky fans! Happy Friday! What’s happening this weekend? Anything fun? I hope so. This is my second post today, so, really, how much more fun can you handle?

Here’s a tip. I can be a numbskull sometimes (really, Scott, you?) and I went off to do some other things thinking I was finished with this post. Turns out, nope. Here it sat, waiting patiently, for hours. Always remember, friends, to hit the Publish button in order to publish your posts. It helps. It was all for a good reason, though. We spent a bunch of time trying to catch up with a Mr. Softee truck as it sped through my town. We were able to catch up with it, but all the waving, horn-hoking, and light-flashing we could put together wasn’t enough to get the driver to stop and sell us ice cream. Next time, right?

Of we go.

Well, we’re just about half way through our last lunation, a full lunar orbit, before this month’s solar eclipse. The evening’s planets, Saturn and Jupiter are behind us toward the west, as the Moon keeps making its way around toward full.

The full Moon usually gets all the press, but I really love a good gibbous. When the Moon is full, it’s high noon, complete with the scruffy gunslingers, the moonshine, and the poker games-gone-wrong across the middle part of the moon. Everything’s big and bright, but the shadows are flattened out, just as they are here when the midday Sun is high overhead.

In the gibbous phases, there’s still plenty of light there, but even with your naked eye, you can see the long mountain shadows stretching off across the vast lava seas.

The stars of the constellation Sagittarius (I spelled it right! The first time!), are nearby, but they’re mostly washed out by the bright moonlight. You might be able to pick out Nunki, the Archer’s second brightest star near the Moon.

If you’re the sort of person who likes to stare off at a mostly blank patch of sky, and maybe tell people what they’re not seeing as they scurry across the street, tonight’s for you! Over in that direction, a little bit to the east of the Moon, is everyone’s friend: the dwarf planet Pluto. You won’t be able to see it, you need some serious lenses for that, though. It’s too far, over 3 billion miles / 4.5 billion km, and too dim. I like knowing things are there, though, even if I can’t see them. I get a certain comfort from knowing where the rest of the family is, I guess.

Over the next couple of nights, the Moon will move into the constellation Capricornus, the… what the heck is that thing? A sea goat? The Full Sturgeon Moon, so named for all the sea fish that are easy to catch at this time of year, is on Monday night here in the US, August 7.

Right around now, you might be able to start to see how this is all playing out. A full lunation is about 28 days. Tonight, the Moon is a couple of days before full. On Monday it’ll be full, which is the point when it’s directly opposite the Sun in the sky and the Sun-Earth-Moon line is perfectly straight. You’ll see the whole of the Moon, to paraphrase one of the 80s’ best songs.

Since we started at the new Moon (a Sun-Moon-Earth line), the full Moon (Sun-Earth-Moon) is half way around the block; the Moon is on the other side of Earth. Half of 28 days is 14 days; two weeks. With the full Moon on the 7th, add in the lunar month’s remaining 14 days (14 + 7) and we’re at Monday the 21st for the next new Moon. I’ve read here and there that the 21st is a big day.

Can you picture what’s going on? Here’s a quick drawing to lend a hand.

Moon phases July/August 2017
Moon phases July/August 2017

This full Moon will be pretty great for another reason. Eclipses come in pairs. Most solar eclipses are either preceded two weeks before or followed by a lunar eclipse two weeks later, and vice versa. If you’ll be in parts of Europe, Africa, Asia, or Australia on Monday, you’ll see a partial lunar eclipse. Not a major one, but a lunar eclipse nevertheless.

Let me see if I can explain this quickly.

The Moon’s orbit around the Earth is tiled by about 5 degrees relative to the ecliptic; the path the Sun takes across the sky. Most of the time, the Moon misses and passes just above or below the Sun, so we don’t eclipses every month. When there’s a solar eclipse, the Moon’s orbit crosses the ecliptic exactly at new Moon and the Earth falls into the Moon’s shadow. Two weeks before or after, the Moon is in just the right place to fall into Earth’s shadow. Poof. Lunar eclipse.

As if that wasn’t enough! While you watch the Moon over these next few nights, look at the sky high above it. The Moon will draw a rough line under Altair, Vega, and Deneb, the three stars of the Summer Triangle, which we’ll talk about another time.

Have a great weekend, and clear skies, everyone!

 

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