public function distance(Location $otherLocation)
    {
        $theta = $this->longitude - $otherLocation->getLongitude();
        $distance = (sin(deg2rad($this->latitude))
            * sin(deg2rad($otherLocation->getLatitude())))
            + (cos(deg2rad($this->latitude))
            * cos(deg2rad($otherLocation->getLatitude()))
            * cos(deg2rad($theta)));
        $distance = acos($distance);
        $distance = rad2deg($distance);

        return (float) $distance * 60 * 1.1515;
    }