How big is a degree lat or long?

I don't know if this is the proper place to ask this, but I was
wondering how big a degree is, on the surface that is. Or where should
I look?

Thanks,
Rob

Rob,

Since the Earth's quarter circumference is roughly 10 000 km, (Earth
radius=6367 km) and is divided in 90 degrees, that gives roughly 111 km in
one degree of latitude (moving North-South). Moving East-West, that distance
reduces to 111km x cos(latitude) - since the meridians converge towards the
poles. Thus 1 arc minute = 1,8km; 1 arc second = 30m. (same cos rule apply)
Makes any sense?
BTW, the original definition of one metre used to be 1/10 000 000 the
quarter circumference of the earth.

P.S. Then there is 1.6 km to the mile.....

Jors.

"Robert Solomon" <rob@drrob1.com> wrote in message
news:MPG.19b1a3a0c08d292f9896aa@news-server.optonline.net...
> I don't know if this is the proper place to ask this, but I was
> wondering how big a degree is, on the surface that is. Or where should
> I look?
>
> Thanks,
> Rob

Robert Solomon wrote in message ...
>I was
>wondering how big a degree is, on the surface that is. Or where should
>I look?
>

a degree of latitude is 60 nautical miles everywhere.

a degree of longitude is 60 Nautical Miles only at the Equator.

if not at the equator then the formula is:

60 * cosine(latitude) = nautical miles per degree of longitude

> I don't know if this is the proper place to ask this, but I was
> wondering how big a degree is, on the surface that is. Or where should
> I look?

Considering the Earth as a sphere, 60 nautical miles was intended to
represent a degree of latitude...

Robert Solomon <rob@drrob1.com> wrote in
news:MPG.19b1a3a0c08d292f9896aa@news-server.optonline.net:

> I don't know if this is the proper place to ask this, but I was
> wondering how big a degree is, on the surface that is. Or where should
> I look?

I'd suggest looking on the Degree Confluence Project website ;-)
Specifically, try this:
http://www.confluence.org/infoconf.php#poles

From that page:
If the Earth were a perfect sphere, the north-south distance between
adjacent pairs of degrees of latitude (parallels; lines that run
east-west) would be the same from the equator to the poles. However,
the east-west distance between adjacent pairs of degrees of longitude
(meridians; lines that run north-south) varies depending on the latitude,
with the maximum distance being at the equator, and the minimum distance
being at the poles, where the lines of longitude meet.

The Earth is not a perfect sphere, and the WGS84 system that we use for
degree confluences includes a mathematical model (GRS80) of the Earth as
an ellipsoid. Using established GRS80 constants, and the Vicenty Algorithm,
the distance between degrees of latitude (lines that run east-west) varies
from 110.57km (68.71mi) at the equator (0 degrees latitude) to 111.69km
(69.40mi) between 89 degrees latitude and the poles.

Using the same calculation methods, the distance between degrees of
longitude (lines that run north-south) varies between 111.32km (69.17mi)
at the equator (0 degrees latitude) to 1.95km (1.21mi) at 89 degrees
latitude, one degree from the north or south pole. Because the lines of
longitude meet at the poles, the distance between degrees of longitude
at the poles is zero.

--
Dave Patton
Canadian Coordinator, the Degree Confluence Project
http://www.confluence.org dpatton at confluence dot org
My website: http://members.shaw.ca/davepatton/
Vancouver/Whistler - host of the 2010 Winter Olympics

On Sat, 23 Aug 2003 21:40:07 GMT, "Craig Davidson"
<nospam@earthlink.com> wrote:
>Robert Solomon wrote in message ...
>>I was
>>wondering how big a degree is, on the surface that is. Or where should
>>I look?
>a degree of latitude is 60 nautical miles everywhere.
>a degree of longitude is 60 Nautical Miles only at the Equator.
>if not at the equator then the formula is:
> 60 * cosine(latitude) = nautical miles per degree of longitude

Mr Davidson's answer is probably the simplest explanation to someone
who isn't far along with coordinates, but might include the suggestion
that a look at a globe bearing lines of longitude or the illustrations
in a primary book on navigation would help to visualize the 'spatial
relations' involved.

And after you wade through all the maths that WGS84 or other different
standards give, the earth isn't even flat except on the sea on a very calm
day. There are mountains and caves and buildings that get in the road. Even
how high you hold your GPS could affect it, but how accurate do you want to
be? These figures are approximate!

Latitude

1 degree
= 60 nautical miles
= 111.12 kilometres
= 111120 metres
= 69.04694 miles
= 364567.8 feet

1 minute
= 1 nautical mile
= 1.852 kilometre
= 1852 metre
= 1.150782 mile
= 6076.131 feet

1 second
= 0.016667 nautical mile (1/60)
= 0.03086667 kilometre
= 30.86667 metres
= 0.01917971 mile
= 101.2688 feet

To work out Longitude, you have to get out your cosine tables or your
calculator. Just multiply the above by the cosine of the degree and it will
give you the distance.

The different models they use all apply a fiddle factor to either or both
latitude and longitude to adjust for a nominal change from a perfect sphere.
You could probably do a search on it and wade through 5000 matches and
eventually find it somewhere. I don't need that accuracy if I'm doing it
with a pencil and paper trying to navigate a plane, and the GPS does it for
me as long as I set it to the one I want to use. Normally this would be
because the map you have uses that setting.

Hope this helps,
Peter

"Bushy" <please@reply.to.group> wrote in message
news:bikh1l$bcp$1@bunyip.cc.uq.edu.au...
> And after you wade through all the maths that WGS84 or other different
> standards give, the earth isn't even flat except on the sea on a very calm
> day.

Well, not really....see:

http://photojournal.jpl.nasa.gov/catalog/PIA04652

Do these anomalies affect the GPS satellites? I realise the effects will be
small.

Comments, anyone?

Peter Seed

Remove my PANTS to reply.