Roundest Object

Sparky49

Joined Jul 16, 2011
833
If one were to be picky; the Earth is round. :p

Taken from the Oxford Dictionary:

"1.2 shaped like a sphere"

Like a sphere suggesting that it shares, but is not limited to the exact qualifications of a [perfect] sphere.

So it would seem that to call the Earth round or spherical would be acceptable, but any mention of the Earth being exactly round or exactly spherical would not.

Also, cool video. :D I find the processes in making something more exacting than ever before very intriguing. A lot of clever people. :)

Sparky
 

Georacer

Joined Nov 25, 2009
5,181
In GPS technology, the exact shape of the Earth is called a "geoid". Quite suitable IMO.

Spheres are not used to approximate the shape of the Earth, but ellipses are used instead.
However, each authority publishes its own ellipsoid, depending on where the ellipsoid surface is wanted to be a more accurate fit of the surface of the Earth. This has geographical criteria.

The world standard right now, the WGS84, is about 120 meters off over India!
 

Thread Starter

Metalmann

Joined Dec 8, 2012
703
"Also, cool video. :D I find the processes in making something more exacting than ever before very intriguing. A lot of clever people."



I remember thinking that, when I first learned to turn a true sphere on a lathe.;):D:cool:
 

#12

Joined Nov 30, 2010
18,167
120 meters...math math math...393.4 feet.
I've mentioned this before but, the first time I had a falling out with my teacher was when I was 7 years old and the latest news from satellite measurements was "600 feet larger circumference in the southern hemisphere". I assume, over 50 years later, they are still teaching that our planet is, "round" in third grade. No child left behind, lowest common denominator, don't confuse them with facts, etc. I really must get over my false expectation that the American public schools will eventually catch up with reality.
 

Sparky49

Joined Jul 16, 2011
833
120 meters...math math math...393.4 feet.
I've mentioned this before but, the first time I had a falling out with my teacher was when I was 7 years old and the latest news from satellite measurements was "600 feet larger circumference in the southern hemisphere". I assume, over 50 years later, they are still teaching that our planet is, "round" in third grade. No child left behind, lowest common denominator, don't confuse them with facts, etc. I really must get over my false expectation that the American public schools will eventually catch up with reality.
By definition of 'round', it is perfectly acceptable to say it is round.

To say that it is perfectly round, however, is not.
 

JoeJester

Joined Apr 26, 2005
4,126
Wouldn't they also need to define an exact spot on the earth where a measurement is taken in order for it to be equal to the official kilogram?
There is a spot that marks the geodetic center of the U.S. in Kansas. There are plenty of datums. In the U.S. there is NAD-27, NAD-83, WGS-84, et al.

Google earth uses WGS-84 as the data as far as I can tell. I will say that due to the flattening of the earth, you will not land on a WGS-84 marker accurately.

There is a Hawaii datum as well. So each country decides on their standard, and should the world decide on a standard, the political infighting will decide on the marker.

I had a friend who stood on the prime meridian in Greenwich with his GPS. It was off until he changed his datum marker from U.S. to Great Britain.
 

t_n_k

Joined Mar 6, 2009
5,447
Yes I know what it means. I do not recall it being mentioned where it was made.
It was pretty subtle. A small title bar came across the screen at the commencement of the video. Ms Katie Green spoke with an Australian accent and it seems works for the Precision Optics division of CSIRO. In any event I was aware of the project a long time ago. I live in Australia.
 
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