text: function calculate(avgAlt, GM, earthRadius) {
    return 2 * Math.PI * Math.sqrt((earthRadius + avgAlt) ** 3 / GM);
  }
  
  export function orbitalPeriod(arr) {
    var GM = 398600.4418;
    var earthRadius = 6367.4447;
    return arr.map(({ name, avgAlt }) => {
      return {
        name,
        orbitalPeriod: Math.round(calculate(avgAlt, GM, earthRadius)),
      };
    });
  }
  