public function calculate(N\LatLong $point1, N\LatLong $point2) {
        $celestialBody = $this->getCelestialBody();
        $degrees = acos(sin($point1->getLatitude()->get()) *
            sin($point2->getLatitude()->get()) +
            cos($point1->getLatitude()->get()) *
            cos($point2->getLatitude()->get()) *
            cos($point2->getLongitude()->get() -
                $point1->getLongitude()->get()));
        $d = $degrees * $celestialBody->volumetricMeanRadius;
        return $d * 1000;
    }