Moon Perigee & Apogee affecting Hydrometer Reading

This is along the same lines as my previous post.

Its a fact that the orbit of the moon varies up to say 5000km during a normal monthy (28day) orbit of the moon - right? The perigee and apogee, (vertical position in reference to the equator), also vary during a 27 day cycle.

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Its also a fact that the Sun also has a gravitational influence on our liquids but it is 2 1/2 times less than the Moon.

So if the moon can afect tides, by pulling water away from the earth due to gravitational influence, can it also affect our Hydrometer readings? Bear in mind that if the moon is pulling at our precious brew at the same force as the ocean, then our brew should be less dense right? If its less dense then our hydrometer will sink more, won't it? If so then we could be getting a false SG reading because the brew will appear a lower SG than it really is.

Lets say it's a Full Moon at its perigee in Cairns - Australia on Dec

22nd 2003, (its also a high tide), and we take a Hydrometer reading at Sea Level with Pressure 1010mb - and it reads SG 0.992, then what will the SG read when the moon is at is apogee on Jan 3rd 2004, at sea level, with the same atmospheric pressure? Might it read higher?

I can hear many say - WHO CARES? But the reality is this, with many wines I have measured the same SG but with noticably slight variations in sweetness when tasting - even though I am using the same juice and methodology for winemaking and the same hydrometer. Some might put it down to variations in the actual juice and differences in yeast colony count, etc...

But could the relative local atmospheric pressure and Moon position influence the accuracy of my SG readings?

Cheers, Steve!

Reply to
OzWineKitz
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Dunno about the moons influence, but sg is basically a reflection of all dissolved substances, of which alcohol and sugar are two. By defenition, a difference in TA of 0.1% would also give a sg difference of 0.001 (g/ml), not much but it's only one of the variables.

My gutfeeling is that the moon doesn't influence the hydrometer at all, as it is measured *relative* to the fluid, it's not an absolute measurement!

Rene.

Reply to
Rene

The moon doesn't attract only the sea, but everything. Since the oceans covers the whole planet, it's influence is more obvious. It doesn't change the "specific gravity" of liquids, it only attracts it like a magnet. If the ships don't float more or less depending on the moon, neither will your hydrometer. As Rene says, it'a a relative reading. The brew and the hydrometer will both have the same influence, and the reading wil be accurate.

Reply to
Willie

I imagine the moon and sun do have an effect on gravity when it comes to your hydrometer. Sure the wine is being pulled up making it less dense, but at the same time the hydrometer itself is being pulled up, making it lighter and more buoyant. The oceans combined is a very large body of water, so the effects are easily noticed. The Great Lakes see tidal action too, but it's minimal. Typical lakes don't see the effect since they are so small. A body of water (or wine in this case) the size of your batch would be affected only on a microscopic level. I'm not a scientist, but this sounds logical.

I live on the beach, on the beautiful BC coast. Is it better for me to rack my wine at high tide or low tide? Like to old wives tale about sauerkraut having to be made under a full moon, should we be pitching our yeast during the waxing? The waning? What would happen if you started a wine during an eclipse for goodness sake? As I said, I'm NOT a scientist, LOL!

Reply to
Dan

Density is the same regardless of the effects of gravity

Reply to
Robert Lee

Ditto. I think when the moon starts affecting winemaking, somebodys overthinking the fermentation situation & letting it get to his imagination. Do ya get the corralation? Made a lotta really good wine in my time & I don't even have a telescope. Good luck.

Reply to
PA-ter

Just for the record, the oceans of the world cover approx 75%, the ice at the poles cover approx 3%, and the land masses cover the other 21%. The moon pulls on ALL things realiveto their weight in accordance with basic physice which determines that the Force is proportional to the weight and the distance squared. This is why the moon also contributes to tectonic plate movement and earthquakes, because even the earth is being pulled by the moon. But the weight of a Hydrometer is far less than the weight of of the wine we are measuring. Therefore the difference is exaggerated some 100+ times, isn't it?

The question remains,what is the difference? What difference does atmospheric pressure impart to ones readings? Does alcohol behave differently at lower SG than say wine? Does anyone know the actual difference and percentages?

Thanks for your imput anyway.

Cheers, Steve!

Reply to
OzWineKitz

If this is truly of concern to you, I am sure you could apply "Solinar Tables" to your calculations. They are the tables calculated from the sun and the moon and maybe a bit of astrology, that predict when fish will bit. They have been used for years by fishermen who need to explain why the fish were not biting. Maybe you could determine when you should pitch your yeast or pick the grapes or something.

;o) Ray

Reply to
Ray

The calendar I have right now has the "poor, good, and best" fishing days shown on each day. The cycle of fishing rates coresponds to the cycles of the moon. The poor days centre around the full moon, the best days centre around the new moon. I think it's is based on the idea that fish will feed at night under the full moon, but not in the dark under a new moon, thus making your day of fishing better or not.

Reply to
Dan

You just completely ignored the previous poster's response...it was completely correct that specific gravity is a measure of DENSITY and density is NOT affected by gravity.

Density is defined a mass/volume

Weight is mass*gravity (f=ma, anyone?)

In your example the apparent gravity, g_a, is equal to the gravity due to the earth, g_e, minus the moon gravity due to the moon, g_m

g_a = g_e - g_m

The weight of the wine is g_a * mass(wine), so yes, the weight of the wine changes (so does the weight of the hydrometer). But buoyancy does not depend on weight...the volume of both the wine and the hydrometer AND the mass of both the wine and hydrometer remain constant.

Thus no effect...end of physics lesson today.

IFbrewer

Reply to
Jeff French

Thanks, after the little tirade above, you've hit it right on the head!

Rob L

Reply to
Robert Lee

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