How do I get compass bearings on google earth?

January 13, 2016 2:50 PM

I need to get accurate compass bearing for my apartment. I purchased a compass, but it is crap and doesn't work.

The compass I bought keeps saying that north is NOT where north is. It was a cheap one, but that was the only one they had. So I want to use google earth instead. It's for this feng shui thing I'm doing. I have to get the bearings for when I turn towards my NORTH windows. I already know they are north, but I guess I need to be more specific than that and get a more precise bearing.

On google earth when I type in my apartment and then go to street view and look towards the direction of my north windows- I don't see any numbers or anything that would indicate a compass bearing.

posted by rancher to Technology (15 answers total)

I'm not sure you can do this in Google Earth. Do you have an iPhone? There's a compass in Extras (or you can swipe down and search for "compass").
posted by wintersweet at 2:56 PM on January 13, 2016 [1 favorite]

Did you adjust for magnetic declination with your compass?
posted by barchan at 2:56 PM on January 13, 2016 [6 favorites]

Yeah, your compass points toward magnetic north, and Google likely orients to geographic north. Depending on where you are (if you're in North America) the difference can be like 20 degrees.

According to my cursory googling, there doesn't seem to much consensus on which to use for Feng Sui, so there you have that.
posted by cmoj at 3:26 PM on January 13, 2016 [2 favorites]

You can probably find some civil engineering source which gives the direction of the streets around your place, if you're along a straight street in a city.

A solar calculator can give you the precise bearing of Sunrise and Sunset given your location and the date.
posted by Sunburnt at 3:50 PM on January 13, 2016

can't you look at the map view in google maps and measure it on the screen using a protractor? north is up.
posted by andrewcooke at 3:57 PM on January 13, 2016 [2 favorites]

Do you have a smart phone? There are free compass apps in both Android and iPhone versions; but they rely on signals from a magnetic sensor in your phone. Like your cheap handheld compass though, that means it will be pointing to magnetic north (not geographic north along a longitude line) - that's easy though, your feng shui books should tell you which they mean. THe trickier thing about magnetic compasses is that they don't work if there is a lot of metal nearby, so they can be thrown off by a steel-framed building structure.
posted by aimedwander at 4:10 PM on January 13, 2016

According to my cursory googling, there doesn't seem to much consensus on which to use for Feng Sui, so there you have that.

My recollection is that lodestones were originally used in China for Feng Shui. So if I had to guess and did not have an official Feng Shui source saying otherwise, I would be inclined to go with magnetic north.

Chinese history: Compass
posted by Michele in California at 4:18 PM on January 13, 2016 [2 favorites]

Actually on contemplation I'd do as andrewcooke suggests, a totally toolless approach. Look out your window and find the farthest object you can see (a tree, a tall building, etc). Point at that direction, and put a line of masking tape on your floor to mark that direction. Then open google maps, and mark your best estimate of the position of your window, and your best estimate of the position of your target object. The farther away your target object is, the less it matters how sloppy your estimates are. Hold a sheet of paper up to the screen with one edge exactly vertical (north), and mark the two points on the paper (felt tip or something soft so you don't damage your monitor). Go over to the piece of tape on your floor, and line up the dots to the edge of the tape. The edge of the paper now marks due north (geographic north).
posted by aimedwander at 4:25 PM on January 13, 2016

Yes, use Google Maps. That's how I learned that true north at my house is 15-20 degrees "left" of where I thought it was - and I later confirmed by going outside at solar noon and setting up a sun dial, which pointed right where Google Maps said it ought to. (I was plotting out a solar array.)
posted by Joey Buttafoucault at 4:26 PM on January 13, 2016

There have already been thousands of years of discussion over the geographic versus magnetic north question, and where each is appropriate. Here is a pretty good reference. It concludes:

All directions are relative. There is no such thing as absolute north (or true north). The astronomical north refers to a moving axis of rotation of the earth. The grid north refers to a standard way of making maps. The magnetic north refers to a moving dipole in the earth. The study of feng shui builds its analysis on superimposing qi fields of which gravity and magnetism are major players. Although feng shui is not a science, it cannot be detached entirely from science. Magnetic field being one of the two most important fields on earth, feng shui has to be based on the magnetic directions. Magnetic north, and not astronomical north, is therefore to be used in measuring directions.

That's just one opinion, but it seems to reflect current consensus.
posted by MoTLD at 4:43 PM on January 13, 2016

Do you happen to live in NYC?

If so, I know a lot of people get confused thinking that the Manhattan street grid is perfectly aligned vertically to North-South, but the island is actually at an angle to the compass directions. So, what many people think of as North (the Bronx is up but the Battery's down) is actually about 29 degrees off.
posted by This_Will_Be_Good at 5:07 PM on January 13, 2016 [3 favorites]

Wait until midday. Look for the sun.
posted by kjs4 at 5:19 PM on January 13, 2016

Leaving aside the issue of magnetic versus geographic north, there are plenty of sites that will do this for you on Google Maps. Here is one that should do what you want.
posted by ssg at 8:35 PM on January 13, 2016

Best answer: If you use the ruler tool in Google Earth and select "line" you can find bearings. The bearings are true so you will need to adjust to magnetic as listed above.

Lines you draw in Earth stay visible when you switch to street view so that can help your troubleshooting.
posted by Crashback at 9:40 PM on January 13, 2016 [3 favorites]

The geomagnetic field is quite lively at the moment, so you might want to recalibrate every few years.
posted by scruss at 6:58 AM on January 14, 2016