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centerSphere.txt
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centerSphere.txt
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=============
$centerSphere
=============
.. default-domain:: mongodb
.. contents:: On this page
:local:
:backlinks: none
:depth: 1
:class: singlecol
.. query:: $centerSphere
.. versionadded:: 1.8
The :query:`$centerSphere` operator is the spherical equivalent
of the :query:`$center` operator. :query:`$centerSphere` uses
spherical geometry to define a circle for use by the
:query:`$within` operator in :term:`geospatial` queries.
To define the bounds of a query using :query:`$centerSphere`, you
must specify:
- The center point
- The angular distance in radians (distance along the surface of the
earth).
Consider the following prototype:
.. code-block:: javascript
db.collection.find( { loc: { $within:
{ $centerSphere:
[ [<long>,<lat>], <distance> / <radius> ]
} } } )
The following example returns all documents within a 10 mile radius
of longitude ``88 W`` and latitude ``30 N``. MongoDB converts the
distance, 10 miles, to radians by dividing by the approximate
radius of the earth, 3959 miles:
.. code-block:: javascript
db.collection.find( { loc: { $within:
{ $centerSphere:
[ [88,30], 10 / 3959 ]
} } } )
.. include:: /includes/note-geospatial-index-must-exist.rst