diff --git a/lib/noosfero/geo_ref.rb b/lib/noosfero/geo_ref.rb
index f7cf2c4..d9ef265 100644
--- a/lib/noosfero/geo_ref.rb
+++ b/lib/noosfero/geo_ref.rb
@@ -1,6 +1,84 @@
 module Noosfero::GeoRef
 
-  KM_LAT = 111.2 # aproximate distance in km for 1 degree latitude
-  KM_LNG = 85.3 # aproximate distance in km for 1 degree longitude
+  # May replace this module by http://www.postgresql.org/docs/9.3/static/earthdistance.html
+
+  EARTH_RADIUS = 6378 # aproximate in km
+
+  class << self
+
+    def dist(lat1, lng1, lat2, lng2)
+      def deg2rad(d); (d*Math::PI)/180; end
+      def c(n); Math.cos(n); end
+      def s(n); Math.sin(n); end
+      lat1 = deg2rad lat1
+      lat2 = deg2rad lat2
+      dlng = deg2rad(lng2) - deg2rad(lng1)
+      EARTH_RADIUS * Math.atan2(
+        Math.sqrt(
+          ( c(lat2) * s(dlng) )**2 +
+          ( c(lat1) * s(lat2) - s(lat1) * c(lat2) * c(dlng) )**2
+        ),
+        s(lat1) * s(lat2) + c(lat1) * c(lat2) * c(dlng)
+      )
+    end
+
+    # Write a SQL expression to return the distance from a profile to a
+    # reference point, in kilometers.
+    # http://www.plumislandmedia.net/mysql/vicenty-great-circle-distance-formula
+    def sql_dist(ref_lat, ref_lng)
+      "2*PI()*#{EARTH_RADIUS}*(
+        DEGREES(
+          ATAN2(
+            SQRT(
+              POW(COS(RADIANS(#{ref_lat}))*SIN(RADIANS(#{ref_lng}-lng)),2) +
+              POW(
+                COS(RADIANS(lat)) * SIN(RADIANS(#{ref_lat})) - (
+                  SIN(RADIANS(lat)) * COS(RADIANS(#{ref_lat})) * COS(RADIANS(#{ref_lng}-lng))
+                ), 2
+              )
+            ),
+            SIN(RADIANS(lat)) * SIN(RADIANS(#{ref_lat})) +
+            COS(RADIANS(lat)) * COS(RADIANS(#{ref_lat})) * COS(RADIANS(#{ref_lng}-lng))
+          )
+        )/360
+      )"
+    end
+
+    # Asks Google for the georef of a location.
+    def location_to_georef(location)
+      key = location.downcase
+      ll = Rails.cache.read key
+      return ll + [:CACHE] if ll.kind_of? Array
+      resp = RestClient.get 'https://maps.googleapis.com/maps/api/geocode/json?' +
+                            'sensor=false&address=' + url_encode(location)
+      if resp.nil? || resp.code.to_i != 200
+        if ENV['RAILS_ENV'] == 'test'
+          print " Google Maps API fail (code #{resp ? resp.code : :nil}) "
+        else
+          Rails.logger.warn "Google Maps API request information for " +
+                            "\"#{location}\" fail. (code #{resp ? resp.code : :nil})"
+        end
+        return [ 0, 0, "HTTP_FAIL_#{resp.code}".to_sym ] # do not cache failed response
+      else
+        json = JSON.parse resp.body
+        if json && (r=json['results']) && (r=r[0]) && (r=r['geometry']) &&
+           (r=r['location']) && r['lat']
+          ll = [ r['lat'], r['lng'], :SUCCESS ]
+        else
+          status = json['status'] || 'Undefined Error'
+          message = "Google Maps API cant find \"#{location}\" (#{status})"
+          if ENV['RAILS_ENV'] == 'test'
+            print " #{message} "
+          else
+            Rails.logger.warn message
+          end
+          ll = [ 0, 0, status.to_sym ]
+        end
+        Rails.cache.write key, ll
+      end
+      ll
+    end
+
+  end
 
 end
diff --git a/test/unit/geo_ref_test.rb b/test/unit/geo_ref_test.rb
new file mode 100644
index 0000000..246c5cc
--- /dev/null
+++ b/test/unit/geo_ref_test.rb
@@ -0,0 +1,62 @@
+# -*- coding: utf-8 -*-
+
+require File.dirname(__FILE__) + '/../test_helper'
+
+class GeoRefTest < ActiveSupport::TestCase
+
+  ll = {
+    salvador:       [-12.9, -38.5],
+    rio_de_janeiro: [-22.9, -43.1],
+    new_york:       [ 40.7, -74.0],
+    tokyo:          [ 35.6, 139.6]
+  }
+
+  should 'calculate the distance between lat,lng points' do
+    assert_equal 1215, Noosfero::GeoRef.dist(*(ll[:salvador]+ll[:rio_de_janeiro])).round
+    assert_equal 6998, Noosfero::GeoRef.dist(*(ll[:salvador]+ll[:new_york])).round
+    assert_equal 17503, Noosfero::GeoRef.dist(*(ll[:salvador]+ll[:tokyo])).round
+  end
+
+  should 'calculate the distance between a lat,lng points and a profile' do
+    env = fast_create Environment, name: 'SomeSite'
+    @acme = Enterprise.create! environment: env, identifier: 'acme', name: 'ACME',
+        city: 'Salvador', state: 'Bahia', country: 'BR', lat: -12.9, lng: -38.5
+    def sql_dist_to(ll)
+      ActiveRecord::Base.connection.execute(
+        "SELECT #{Noosfero::GeoRef.sql_dist ll[0], ll[1]} as dist" +
+        " FROM profiles WHERE id = #{@acme.id};"
+      ).first['dist'].to_f.round
+    end
+    assert_equal 1215, sql_dist_to(ll[:rio_de_janeiro])
+    assert_equal 6998, sql_dist_to(ll[:new_york])
+    assert_equal 17503, sql_dist_to(ll[:tokyo])
+  end
+
+  def round_ll(ll)
+    ll.map{|n| n.is_a?(Float) ? n.to_i : n }
+  end
+
+  should 'get lat/lng from address' do
+    Rails.cache.clear
+    ll = Noosfero::GeoRef.location_to_georef 'Salvador, Bahia, BR'
+    assert_equal [-12, -38, :SUCCESS], round_ll(ll)
+  end
+
+  should 'get and cache lat/lng from address' do
+    Rails.cache.clear
+    ll = Noosfero::GeoRef.location_to_georef 'Curitiba, Paraná, BR'
+    assert_equal [-25, -49, :SUCCESS], round_ll(ll)
+    ll = Noosfero::GeoRef.location_to_georef 'Curitiba, Paraná, BR'
+    assert_equal [-25, -49, :SUCCESS, :CACHE], round_ll(ll)
+  end
+
+  should 'notify a non existent address' do
+    Rails.cache.clear
+    orig_env = ENV['RAILS_ENV']
+    ENV['RAILS_ENV'] = 'X' # cancel throw for test mode on process_rest_req.
+    ll = Noosfero::GeoRef.location_to_georef 'Nowhere, Nocountry, XYZ'
+    ENV['RAILS_ENV'] = orig_env # restore value to do not mess with other tests.
+    assert_equal [0, 0, :ZERO_RESULTS], round_ll(ll)
+  end
+
+end
--
libgit2 0.21.2