Usuari:Pere prlpz/The center of the Earth according to Wikipedia

Vegeu també: Usuari:Pere prlpz/El centre de la Terra segons la Viquipèdia

The centre of the Earth is in Morocco. It's about 2400 below a point in Khouribga Province, but that is just the centre of the Earth according to English language Wikipedia. According to German language Wikipedia, it's 1200 km under a point in western Sardinia, according to Japanese language Wikipedia it lies on the Shaanxi-Henan border (China), and according to Russian language Wikipedia it's in Bulgaria. How do we find the centre of the Earth? Just like we find the centre (or centroid) of anything else: we find where is every point on it, we compute its coordinates and we average them for all points. And what do we use to find where are the points on Earth? Wikipedia, but since articles with coordinates are unevenly distributed across the Earth's surface and the articles with coordinates are different for every edition of Wikipedia, by computing the centre of the geolocated articles from different Wikipedias we get different points according to their diverse content.

Results

Here is a list with the centroids of geolocated articles from several Wikipedias. There is a location map below, but more detailed maps can be gotten by clicking in the "OSM", "Google Maps" or "Bing" links at right.

Centre

Wiki	Punts	Profunditat (km)	Prof (% de radi)	Coordenades	Data de les dades
afwiki	9.684	2.566	40.27%	15° 20′ 16″ N, 17° 26′ 37″ E	Fri Dec 25 10:06:04 2015
alswiki	8.619	367	5.76%	44° 32′ 32″ N, 7° 58′ 13″ E	Fri Dec 25 10:06:16 2015
anwiki	14.046	294	4.61%	40° 32′ 01″ N, 1° 12′ 24″ O	Fri Dec 25 10:06:29 2015
arwiki	93.528	1.927	30.24%	36° 07′ 30″ N, 3° 17′ 05″ E	Fri Dec 25 10:07:16 2015
astwiki	3.538	1.453	22.80%	33° 18′ 11″ N, 5° 56′ 25″ O	Fri Dec 25 10:07:24 2015
azwiki	14.249	1.119	17.57%	36° 35′ 19″ N, 41° 53′ 30″ E	Fri Dec 25 10:07:39 2015
bewiki	40.825	616	9.66%	45° 56′ 56″ N, 23° 21′ 31″ E	Fri Dec 25 10:08:02 2015
bgwiki	47.054	1.369	21.48%	37° 52′ 36″ N, 9° 50′ 34″ E	Fri Dec 25 10:09:25 2015
bowiki	995	2.836	44.52%	23° 17′ 36″ N, 61° 39′ 09″ E	Fri Dec 25 10:10:33 2015
brwiki	15.672	895	14.05%	39° 53′ 27″ N, 0° 29′ 11″ E	Fri Dec 25 10:10:47 2015
bswiki	15.211	554	8.69%	40° 54′ 26″ N, 15° 52′ 02″ E	Fri Dec 25 10:11:58 2015
cawiki	159.152	974	15.30%	40° 17′ 45″ N, 6° 18′ 12″ O	Fri Dec 25 10:13:15 2015
cebwiki	58.331	2.214	34.74%	23° 47′ 36″ N, 5° 10′ 25″ E	Fri Dec 25 10:13:53 2015
cowiki	1.583	899	14.10%	37° 29′ 39″ N, 0° 48′ 15″ E	Fri Dec 25 10:14:33 2015
crhwiki	1.880	502	7.88%	42° 20′ 55″ N, 30° 29′ 02″ E	Fri Dec 25 10:14:44 2015
cswiki	75.061	839	13.16%	43° 11′ 18″ N, 13° 39′ 37″ E	Fri Dec 25 10:16:25 2015
cywiki	20.767	581	9.12%	46° 34′ 41″ N, 0° 25′ 57″ O	Fri Dec 25 10:17:43 2015
dawiki	41.100	985	15.46%	44° 17′ 52″ N, 8° 33′ 04″ E	Fri Dec 25 10:18:08 2015
dewiki	366.644	1.197	18.80%	40° 03′ 33″ N, 8° 42′ 07″ E	Fri Dec 25 10:21:07 2015
elwiki	16.910	1.141	17.90%	34° 29′ 19″ N, 17° 13′ 25″ E	Fri Dec 25 10:21:33 2015
enwiki	982.215	2.399	37.66%	33° 10′ 58″ N, 6° 49′ 48″ O	Fri Dec 25 10:29:16 2015
eowiki	80.982	1.243	19.50%	37° 34′ 03″ N, 5° 55′ 44″ E	Fri Dec 25 10:30:23 2015
eswiki	268.782	2.113	33.17%	30° 26′ 17″ N, 32° 02′ 06″ O	Fri Dec 25 10:32:38 2015
etwiki	27.278	1.094	17.17%	44° 25′ 20″ N, 20° 02′ 12″ E	Fri Dec 25 10:32:57 2015
euwiki	70.861	704	11.05%	41° 56′ 54″ N, 0° 03′ 11″ E	Fri Dec 25 10:33:33 2015
fawiki	137.132	2.022	31.74%	34° 12′ 21″ N, 23° 11′ 22″ E	Fri Dec 25 10:34:47 2015
fiwiki	41.526	1.547	24.29%	39° 04′ 50″ N, 17° 40′ 37″ E	Fri Dec 25 10:35:14 2015
fowiki	2.552	1.263	19.83%	42° 56′ 20″ N, 4° 15′ 19″ E	Fri Dec 25 10:35:23 2015
frwiki	363.912	1.358	21.32%	37° 32′ 16″ N, 3° 55′ 50″ E	Fri Dec 25 10:38:09 2015
furwiki	959	511	8.02%	41° 48′ 55″ N, 11° 17′ 44″ E	Fri Dec 25 10:38:17 2015
gawiki	12.846	798	12.53%	45° 48′ 45″ N, 2° 37′ 31″ O	Fri Dec 25 10:39:28 2015
glwiki	17.437	1.922	30.17%	31° 57′ 17″ N, 1° 12′ 56″ E	Fri Dec 25 10:39:42 2015
hewiki	21.603	1.827	28.67%	33° 01′ 20″ N, 16° 22′ 11″ E	Fri Dec 25 10:39:58 2015
hiwiki	9.196	1.753	27.52%	26° 28′ 45″ N, 62° 13′ 13″ E	Fri Dec 25 10:40:10 2015
hrwiki	32.978	1.560	24.49%	37° 58′ 15″ N, 2° 23′ 26″ E	Fri Dec 25 10:40:27 2015
huwiki	122.159	463	7.27%	44° 06′ 08″ N, 7° 41′ 46″ E	Fri Dec 25 10:41:24 2015
hywiki	78.004	758	11.90%	44° 17′ 39″ N, 23° 23′ 14″ E	Fri Dec 25 10:42:04 2015
idwiki	55.848	2.540	39.87%	24° 57′ 57″ N, 55° 00′ 23″ E	Sat Dec 26 08:30:08 2015
iswiki	5.018	1.455	22.85%	40° 05′ 53″ N, 2° 10′ 43″ E	Fri Dec 25 10:43:14 2015
itwiki	255.311	1.448	22.72%	36° 01′ 02″ N, 5° 43′ 10″ E	Fri Dec 25 10:45:12 2015
jawiki	115.519	2.228	34.98%	34° 06′ 44″ N, 110° 38′ 50″ E	Fri Dec 25 10:46:28 2015
kawiki	27.433	2.549	40.02%	25° 27′ 20″ N, 2° 07′ 42″ O	Fri Dec 25 10:46:47 2015
kkwiki	77.680	959	15.05%	40° 59′ 40″ N, 0° 44′ 52″ E	Fri Dec 25 10:47:24 2015
kowiki	43.933	2.678	42.03%	31° 28′ 09″ N, 81° 27′ 28″ E	Fri Dec 25 10:48:07 2015
kuwiki	3.324	986	15.48%	34° 48′ 17″ N, 34° 55′ 43″ E	Fri Dec 25 10:48:21 2015
lawiki	58.043	378	5.94%	44° 19′ 50″ N, 3° 21′ 05″ E	Fri Dec 25 10:48:55 2015
lbwiki	12.528	463	7.27%	43° 29′ 07″ N, 3° 39′ 33″ E	Fri Dec 25 10:49:08 2015
lmowiki	23.773	204	3.20%	43° 48′ 07″ N, 8° 22′ 53″ E	Fri Dec 25 10:49:26 2015
ltwiki	34.017	1.721	27.02%	35° 10′ 14″ N, 17° 15′ 54″ E	Fri Dec 25 10:49:47 2015
lvwiki	13.724	1.434	22.51%	37° 59′ 36″ N, 19° 37′ 39″ E	Fri Dec 25 10:50:00 2015
minwiki	2.385	1.405	22.06%	19° 09′ 10″ N, 73° 47′ 10″ E	Fri Dec 25 10:50:09 2015
mkwiki	18.606	959	15.05%	40° 37′ 14″ N, 18° 18′ 13″ E	Fri Dec 25 10:50:35 2015
mnwiki	3.024	1.803	28.30%	34° 52′ 53″ N, 74° 47′ 25″ E	Fri Dec 25 10:50:44 2015
mswiki	154.439	1.028	16.14%	37° 14′ 12″ N, 24° 53′ 28″ E	Fri Dec 25 10:52:08 2015
newwiki	13.968	3.110	48.82%	28° 46′ 54″ N, 77° 13′ 03″ E	Fri Dec 25 10:52:21 2015
nlwiki	337.518	1.572	24.68%	36° 49′ 45″ N, 9° 24′ 21″ E	Fri Dec 25 20:31:59 2015
nnwiki	52.400	3.150	49.44%	17° 48′ 01″ N, 12° 02′ 45″ E	Fri Dec 25 20:32:17 2015
nowiki	78.361	2.019	31.69%	34° 51′ 57″ N, 2° 35′ 42″ E	Fri Dec 25 20:32:43 2015
ocwiki	56.873	353	5.54%	42° 48′ 54″ N, 1° 47′ 56″ E	Fri Dec 25 20:33:00 2015
plwiki	339.641	939	14.74%	42° 29′ 30″ N, 9° 31′ 50″ E	Fri Dec 25 20:34:23 2015
pmswiki	44.353	218	3.43%	45° 29′ 32″ N, 2° 49′ 21″ E	Fri Dec 25 20:34:39 2015
ptwiki	188.724	1.777	27.89%	32° 57′ 17″ N, 14° 01′ 47″ O	Fri Dec 25 20:35:23 2015
rmwiki	2.434	677	10.62%	41° 13′ 27″ N, 4° 34′ 41″ E	Fri Dec 25 20:35:31 2015
rowiki	163.635	711	11.16%	40° 38′ 56″ N, 11° 58′ 25″ E	Fri Dec 25 20:37:11 2015
ruwiki	316.123	1.060	16.63%	43° 11′ 52″ N, 25° 39′ 01″ E	Fri Dec 25 20:39:21 2015
scwiki	1.943	1.224	19.22%	36° 04′ 53″ N, 1° 27′ 34″ O	Fri Dec 25 20:39:31 2015
sewiki	3.198	1.002	15.72%	46° 31′ 10″ N, 10° 32′ 08″ E	Fri Dec 25 20:39:40 2015
shwiki	279.518	1.956	30.69%	32° 55′ 50″ N, 51° 45′ 41″ O	Fri Dec 25 20:41:47 2015
skwiki	76.786	431	6.76%	44° 30′ 33″ N, 7° 44′ 09″ E	Fri Dec 25 20:42:10 2015
slwiki	32.745	352	5.53%	43° 31′ 56″ N, 14° 33′ 49″ E	Fri Dec 25 20:44:24 2015
sqwiki	17.630	1.033	16.21%	41° 58′ 18″ N, 5° 17′ 22″ O	Fri Dec 25 20:44:37 2015
srwiki	157.340	986	15.48%	42° 39′ 54″ N, 4° 03′ 54″ O	Fri Dec 25 20:45:17 2015
svwiki	204.400	1.426	22.38%	39° 51′ 35″ N, 10° 40′ 40″ E	Fri Dec 25 20:46:35 2015
thwiki	10.740	2.656	41.69%	25° 27′ 59″ N, 77° 24′ 45″ E	Fri Dec 25 20:46:48 2015
tkwiki	805	1.467	23.02%	30° 56′ 54″ N, 38° 59′ 55″ E	Fri Dec 25 20:47:55 2015
trwiki	37.560	1.113	17.46%	36° 43′ 57″ N, 24° 36′ 11″ E	Fri Dec 25 20:48:13 2015
ukwiki	190.068	679	10.66%	43° 53′ 59″ N, 18° 20′ 55″ E	Fri Dec 25 20:58:08 2015
uzwiki	72.298	897	14.08%	44° 00′ 18″ N, 11° 42′ 07″ O	Fri Dec 25 20:58:29 2015
viwiki	175.333	1.933	30.34%	36° 07′ 05″ N, 5° 31′ 20″ E	Fri Dec 25 20:59:16 2015
vlswiki	1.274	470	7.38%	45° 49′ 18″ N, 4° 55′ 30″ E	Fri Dec 25 20:59:24 2015
vowiki	108.378	1.103	17.31%	40° 56′ 07″ N, 20° 50′ 40″ O	Fri Dec 25 21:00:29 2015
wawiki	1.476	633	9.94%	41° 45′ 02″ N, 6° 24′ 00″ E	Fri Dec 25 21:01:37 2015
warwiki	102.974	999	15.69%	38° 32′ 51″ N, 0° 25′ 48″ E	Fri Dec 25 21:02:10 2015
wikidata	2.385.879	1.703	26.73%	38° 44′ 07″ N, 5° 59′ 17″ E	Sat Dec 26 08:43:13 2015
zhwiki	225.888	2.851	44.75%	27° 45′ 40″ N, 40° 01′ 41″ E	Sat Dec 26 08:45:56 2015

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wikidata

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The center of the Earth according to each Wikipedia

Depth of centre is related to how spread are points from each Wikipedia. An edition of Wikipedia with articles evenly spread over the globe would yield a very deep centre that would fit the geometric centre of the Earth. A similar centre could be produced by a Wikipedia with articles clustered in a pair of areas placed in each other's antipodes.

Although deeper research would be needed to fully explain every centre, in general the centre from each Wikipedia can be explained from its content in three areas where most Wikipedias have a lot of geolocated articles:

• The area where the language of each Wikipedia is spoken.
• Europa, specifically Western Europa.
• North America and specifically the United States.

The remaining continental areas influence seems to be smaller.

This way, most Wikipedias produce centres arround the Mediterranean Sea (most of them Western Mediterranean), with some notable exceptions:

• Wikipedias in non-European languages: The big distance from the central (Mediterranean) zones and their linguistic areas produces a centre in some point between both and at great depth. Notably, South Eastern Asia languages and Afrikaans have centres moved to their areas. Spanish and Portuguese Wikipedia can be included in this group, since their American linguistic areas carries the centrer to the Atlantic Ocean.
• Botopedias: Wikipedias with hundreds of thousands of bot-made geographical stubs produce centres far from their linguistic area but close to the place where stubs are. An extreme case is Serbo-croatian Wikipedia with its mid Atlantic centre -the westernmost of all centres- because one third of geolocated articles in shwiki are Mexican places. Volapük Wikipedia, the oldest botopedia, shows a similar Atlantic centre.

Only a few Wikipedias yield a center in its own area: only Arabic, Occitan and Aragonese Wikipedias, probably because of a combination of local content and a location that makes the effect of other geolocated articles cancell. Not surprisingly, Arabic, Occitant and Aragonese languages are spoken in the Western Mediterranean areas where the centers of most Wikipedias lie.

The center of all Wikidata items with coordinates is in the Mediterranean Sea in front of the Algerian coast, among the centers of most Wikipedias but less deep than most of them. That's not far away from where it would be expected, but it would be interesting to see where are located the items that are in Wikidata and not in any Wikipedia.

Finding the centers

The program used to get the data, do the math and format the table and the location map is Usuari:PereBot/robot centre viquipèdies.

Data

Data for each Wikipedia are coordinates of all items in Wikidata with links to that Wikipedia. Items are filtered out using astronomical body property to only include items without this property and items with it filled with value Earth - when data were retrieved very few Earthly items had this property.

Items with coordinates in Wikidata aren't exactly the same items that show coordinates in their articles in Wikipedias, and when there are coordinates in Wikipedias and Wikidata they aren't always the same. Although, given that some bots upload coordinades from Wikipedias to Wikidata and that usually coordenates in Wikidata don't bear more errors than in Wikipedia, differences are expected to be small and aggregate measures -like centers or counts- of both sets of coordinates should be very similar.

Other works on geolocation in Wikipedias have used all coordinates appearing in articles, retrieved from template {{coord}} and the links it produces. The most notable difference with data used here is that we are using just one point for each article (and item) while other works used more than one point when the article had more than one geolocated point. Basically, this supposes that we are ignoring the points from lists with coordinates (example).

The math

Wikidata stores geographical coordinates (latitude and longitude) for each item. They are used to compute Cartesian coordinates (x,y,z) in a reference frame with origin in the center of the Earth, which is taken as a sphere with radius equal to one. Cartesian coordinates for all points are averaged to find the center and its coordinates are again converted to geographical ones (latitude, longitude and radius).

This way of finding (and defining) the centroid of the geolocated articles in a given Wikipedia has three consequences:

• The definition of the center of a set of points depends on the definition of distance between two points. Here the Euclidian distance is used - that is, the distance along an straight line across the Earth. Had been used a distance measured along a great circle -the distance on the surface of the Earth- slightly different centers had been obtained.
• The Earth is approximated by a sphere. Since the biggest difference between mean radius and real local radius is about 15 km, the error caused by this approximation can be expected to be even smaller - I would guess a lot smaller.
• Height above (or under) sea level has not been used because this piece of information is seldom stored in Wikidata. However, most of geolocated items are placed just a few hundred meters above sea level so the error caused by ignoring height is expected to be a lot smaller than one kilometer.

See also

• List_of_Wikipedias, in Meta.