How can I find true north from my house?
I tried with my phone a few years ago and got different readings on different days
Are some apps better than others?
How accurate would a Silva compass be, and where has magnetic north gone?
Advice please George
apps should all be the same, maybe your phone's magnetometer needs re-calibration, usually done by waving it around in a large 'figure 8' pattern
or use an analogue watch (set to GMT) point hour hand at sun, south is midway between hour hand and 12
How accurately do you need to know?
Solar transit is good to a fraction of a degree. Tomorrow Sun 29th Nov it will be at 11:53:53
Look up "Equation of time" to get the true time of meridian transit relative from local noon in mean solar time. You get rather beautiful pictures of the analemma if you take a series of shots from the same position at exactly 12 noon local time every day.
Magnetic north has been on walkabout lately so for precise results you cannot rely on the offset marked on an OS map any more. Worse in N America - they are nearer the magnetic north pole.
If you want better than solar transit then stellar transit in a good telescope can give you the answer to fractions of an arc second which was the original purpose of the Royal Greenwich Observatory.
Use google maps. Select satellite view and zoom in on your house. Pick a landmark that's due north and look towardsit.
The Pole Star should be pretty good, you just need a clear night. It's within a a degree of true North and is quite easy to find.
Interesting that some old clocks and timepieces had an Equation OF Time dial so that if you lacked an accurate source (eg the BBC news) then by noting the overhead position of Sol together with the equation you could set your clocks to GMT.
... remembering ... What is yellow and always points to the North?
... a magnetic banana :-)
If "reasonably" accurate is good enough then wait for a sunny day and use the shadow of a vertical stick at midday UTC. If you can't wait for midday then remember the earth rotates at 15 degrees per hour. Alternatively, use a magnetic compass to find magnetic north (make sure nothing magnetised or ferrous is within a few feet) and then apply magnetic variation (also called declination) for your location
You can use a watch If you carry a functioning Analog wrist watch, then you can use it to find your North & South directions! A little known trick, but very handy. Hold your watch flat and point the hour hand towards the sun. Bisect the angle between the hour hand and the twelve o'clock mark to get the north-south line Good luck actually finding the sun!
People of a certain age might still have a pair of Clarks Wayfinder shoes :-)
Every Sky and freesat dish points 28.2 degrees east when looking south :-)
Look at a mapping website (Google, Bing, Apple, etc.).
Located your property and zoom in as far as you can.
Look for something identifiable that is north of your house. You can then stand at, say, a corner of your house and look towards the thing you have identified. Might work better if you switch to satellite imagery.
Or, use the local council! Go on their website to report a faulty streetlight. Chances are this will give to access to the very large scale OS map of the area. Pick a landmark that's due north and look towards it. If you don't have a good view find south or east or west and figure it out from there.
Bill
Yes it's to the north.
Bill
Not quite, because we aren't at the centre of the earth.
Bill
Or even measure the angle to North of a straight outside wall of the house, on a decent scale map.
The world is not flat however. I do not want to get into great circle calculations. It hurts my brain. Surely unless you are trying to use north for targeting missiles with no guidance systems, ordinary compasses are fine. The normally have true north and magnetic north. OK so magnetic north moves about due to the internal bit where the field is generated being liquid, but for all intents and purposes that would do.
There are local variations of course due to other objects that are magnetic nearby, but when I was young, I'm sure we could make a pretty good hand at navigation using a compass and a decent map. Brian
Ha, ha. More to the point the 'handle' of the plough points to it. A quick web search shows how easy it is to find the pole star.
Martin Brown has brought this to us :
Does a typical phone app make allowances for magnetic variation? I don't remember being asked to 'allow access to location' when using the compass, which would be needed to allow for the variation.
Martin Brown presented the following explanation :
It certainly is on walkabout. Last time I could be bothered to work it out, I thought I got a local result of around 7 degrees. The NOAA calculator suggests it is now 0 deg 32 min W and due to be on the nose in around 3 years.
Andrew used his keyboard to write :
Not quite, the actual angle depends on how far north you are of the equator.
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