big dipper as timepiece?

[Porcupine]

when i was smoking outside last night i started thinking.

all constellations rotate around the north star (polaris) and the big dipper seems to be in the correct position for the hourhand of the clock.

if you lie with your head north and feet south it seems to be a big clock (if your in western europe).

did i just reinvent something or is the stellar rotation not 24 hours?

 

[Neanderthal]

Porcupine

If only it was that simple. Do a Google search for Star Clock there are lots of links. Once you have got into the habit it is good to about 15 minutes accuracy.

Just been outside into the garden for a quick look. Had to wait until the security lights went off again...

OK. Using the pointers as the hour hand and Polaris as the center of the clock face it is about 5 o'clock (12 hour clock).

Adding 1 hour per month from March 7th (Remember this date).
=7 3/4 to October 27th

So 5+7 3/4=12 3/4

Double the time as it is a 24 hour clock
12 3/4 x 2=25 1/2

Subtract from 24 (or 48 if necessary)
48-25 1/5=22 1/2 i.e. Half past 10. My watch says 11 o'clock so not too bad.

Have fun.

Stu

 

[ridge rover]

Ron Hood covers this in one of his videos. He even has Halle-Bopp on film as he was teaching this lesson.

 

[Porcupine]

hummz, shame it wasnt that easy thanks for clarifying though :You_Rock_

ill be trying this on my next smoke outings,

 

[Walks with dogs]

I was intrigued by this so tried it last night as I let the dogs out.
The big dipper pointers loooked to be at about 5oclock.
I added 7 3/4 ( months from 7th March) and got to 12 3/4.
Multiply by 2 gives 25 1/2
48 minus 25 1/2 = 22 1/2 - half past ten.

Actual time on my watch , quarter to elleven!

I was pretty pleased with myself.

 

[Glen]

For those that don't like mental arithmatic, but maybe are more visual, there's a way of using your visualisation to do some of the maths for you and therefore reading the clock faster.

Using this method you can also work out your seasonal offest before you set out ( it's good for about a week at a time ) or look up, meaning far less confusing in juggling numbers in your head.

In this method the seasonal offset is how long _to_ March 7 times by 2 ( for 31 Oct that's 4 1/4X2 = 8 1/2 )

Now read the pointer stars as though it's a backwards 24 hour clock.
add your seasonal offset and your done.

In the example above the posistion 5O'clock or a normal 12 hour clock would be 14 on a reversed 24 hours dial

14 + seasonal offset of 8 1/2 = 22 1/2 or 10:30 PM

 

[Doc]

Didn't know any of this - good work guys.

I did figure it should be possible to find my latitude from measuring the angle between the horizon and Polaris. I don't have a sextant but I guess a clinometer on a compass, or a home made job with a protractor, would suffice.

Then again, you would have to allow for elevation and so on, and go to the coast to get a true horizon. In any case, getting accurate to 2 degrees would be difficult, which if I recall right amounts to a positional error of 120 nautical miles.

Where's the GPS?

 

[Humpback]

I use the dipper to tell the time by lifting my arm up, palm away from me and putting thumb and forefinger around the constellation as if picking it from the sky.
It has to be my left arm as this one has the wrist watch on it.
Sorry
Alan

 

[Andy2112]

Alan, nice one mate, sorry guys just had to laugh at that one.

 

[fishfish]

Porcupine

If only it was that simple. Do a Google search for Star Clock there are lots of links. Once you have got into the habit it is good to about 15 minutes accuracy.

Just been outside into the garden for a quick look. Had to wait until the security lights went off again...

OK. Using the pointers as the hour hand and Polaris as the center of the clock face it is about 5 o'clock (12 hour clock).

Adding 1 hour per month from March 7th (Remember this date).
=7 3/4 to October 27th

So 5+7 3/4=12 3/4

Double the time as it is a 24 hour clock
12 3/4 x 2=25 1/2

Subtract from 24 (or 48 if necessary)
48-25 1/5=22 1/2 i.e. Half past 10. My watch says 11 o'clock so not too bad.

Have fun.

Stu

jeez !!!!!lost me there! i think ille get a cheapy 99p watch of th market!

 

[saddle_tramp]

and il just ask fish what time it is

 

[Walks with dogs]

I use the dipper to tell the time by lifting my arm up, palm away from me and putting thumb and forefinger around the constellation as if picking it from the sky.
It has to be my left arm as this one has the wrist watch on it.
Sorry
Alan

Now that made me laugh!

 

[rik_uk3]

Carry a wrist watch as back up for when its cloudy

 

[Steve27752]

Too complicated................................Buy a watch!

 

[Walks with dogs]

It is complicated, so is making cordage ( buy some string) , making a fire ( buy a lighter) , or building a shelter ( buy a tent).

Its knowing how to do these things withut he modern trappings that makes it all fun to me.

 

[Neanderthal]

For those that don't like mental arithmatic, but maybe are more visual, there's a way of using your visualisation to do some of the maths for you and therefore reading the clock faster.

Using this method you can also work out your seasonal offest before you set out ( it's good for about a week at a time ) or look up, meaning far less confusing in juggling numbers in your head.

In this method the seasonal offset is how long _to_ March 7 times by 2 ( for 31 Oct that's 4 1/4X2 = 8 1/2 )

Now read the pointer stars as though it's a backwards 24 hour clock.
add your seasonal offset and your done.

In the example above the posistion 5O'clock or a normal 12 hour clock would be 14 on a reversed 24 hours dial

14 + seasonal offset of 8 1/2 = 22 1/2 or 10:30 PM

Cheers Glen.

Anything to reduce the math.

Stu

 

[Porcupine]

Didn't know any of this - good work guys.

I did figure it should be possible to find my latitude from measuring the angle between the horizon and Polaris. I don't have a sextant but I guess a clinometer on a compass, or a home made job with a protractor, would suffice.

Then again, you would have to allow for elevation and so on, and go to the coast to get a true horizon. In any case, getting accurate to 2 degrees would be difficult, which if I recall right amounts to a positional error of 120 nautical miles.

Where's the GPS?

horizon should be easily replaced with a plumb-bob,set squares are easy to get.
knowing 2 of the 3 angles is enough to find the missing angle.

or am i woolgathering again?

 

[rik_uk3]

I use the dipper to tell the time by lifting my arm up, palm away from me and putting thumb and forefinger around the constellation as if picking it from the sky.
It has to be my left arm as this one has the wrist watch on it.
Sorry
Alan

What he said

 

[hog]

Interesting but complicated...what were you smoking by the way?