Finding north

[greenkat]

Just been sat out in back garden and that big yellow thing that pops out occasionaly was shining down.

Just wondered, is it possible to use the shadow of the sun to mark a north/south line on the ground at midday? or would it not be very accurate ?

Reason I ask, I cant see Polaris at night due to my house being in the way

Cheers

[legion48]

I think a compass is your best bet.

[Jeff RV]

If you set up in the exact position, you could mark Polaris earlier with two poles one a small distance in front of your scope centre and one behind, if you get my meaning, acting as a line of sight, Pole/Scope/pole/Polaris.

Jeff.

PS, Or two poles in front if you enough clearance

[Astro_Baby]

Compass or GPS.

A compass may be put off though as they easily affected by stuff with metal work in it and that includes houses - it would stil be more accurate I suspect than marking the suns position.

You could always find Polaris from the other side of the house where you have a North view and line up on something thats visible in the back garden as well OR get a bearing from the house itself. ie if you know by observation where POlaris lies in respect of the houses walls then you should be able to get a good fix on that.

ie in my flat I know Polaris is at a right angle to the back wall of the flat. So I aim the scope for alignment at POlaris from the back of the flat and therefore if I set up in the lounge which has a good western view I know if the RA axis is aimed at 90' to the back wall that I am on target for Polaris. I already have the altitude set from the back of the flat so its only a case of knowing where North is.

[Jeff RV]

Compass or GPS.

A compass may be put off though as they easily affected by stuff with metal work in it and that includes houses - it would stil be more accurate I suspect than marking the suns position.

You could always find Polaris from the other side of the house where you have a North view and line up on something thats visible in the back garden as well OR get a bearing from the house itself. ie if you know by observation where POlaris lies in respect of the houses walls then you should be able to get a good fix on that.

ie in my flat I know Polaris is at a right angle to the back wall of the flat. So I aim the scope for alignment at POlaris from the back of the flat and therefore if I set up in the lounge which has a good western view I know if the RA axis is aimed at 90' to the back wall that I am on target for Polaris. I already have the altitude set from the back of the flat so its only a case of knowing where North is.

He only needs to have two pre aligned holes to place a couple of long broom handles in with markings on a line of sight, the low marking will represent the ep centre, and the higher mark the front centre, the angle can be then drawn up from this but is available from he's position anyway (i think). This will only offer rough alignment though, but is as accurate as a compass, and will always be near on, and cheap.

Jeff.

[Reggie]

Can't you do a 1 star or 2 star alignment on the etx90? Or does it have an option to do a solar alignment? Not sure if the etx will do it, my celestron 6SE does. the one star or solar aligment would be better (the latter with adequate objective end filtering!) with a quick alignment you could then slew to north which would allow you to mark it for future reference.

[George]

Go to this site http://www.solar-noon.com

Input your your local details and you will get a solar calender for your location.

@ solar noon the sun is precisely @ celestial south, using a stick you can mark celestial north, this is more accurate than a compass due to local magnetic variations.

I used this method to orientate my observatory during contruction