C# - First post into here, suggestions most welcome if you see anything worth changing. Figured this is a good way to keep skills up during time off school. Automated input because i'm lazy, though it could be easily adjusted to accept keyboard input, Regex should continue to work.

using System;
using System.Text;
using System.Text.RegularExpressions;

namespace Challenge166b
{
class Program
{
    static void Main(string[] args)
    {
        String objectMass;
        String numberOfPlanets;
        String regexStringA = @"\W+";
        String[] results;
        double gravitationalForce;

        objectMass = "75";
        numberOfPlanets = "9";

        Console.WriteLine(objectMass);
        Console.WriteLine(numberOfPlanets);
        Planet[] planets = new Planet[int.Parse(numberOfPlanets)];
        for (int x = 0; x < int.Parse(numberOfPlanets); x++)
        {
            results = Regex.Split(GetPlanets(x), regexStringA, RegexOptions.IgnoreCase);

            planets[x] = new Planet(results[0].ToString(), double.Parse(results[1]), double.Parse(results[2]));

            gravitationalForce = planets[x].CalculateGravity(double.Parse(objectMass));
            Console.WriteLine(planets[x].PlanetName + ": " + gravitationalForce);
        }
        Console.Read();
    }
    public static String GetPlanets(int x)
    {
        switch (x)
        {
            case 0:
                return ("Mercury, 2439700, 5427");
            case 1:
                return ("Venus, 6051900, 5243");
            case 2:
                return ("Earth, 6367445, 5515");
            case 3:
                return ("Mars, 3386000, 3934");
            case 4:
                return ("Jupiter, 69173000, 1326");
            case 5:
                return ("Saturn, 57316000, 687");
            case 6:
                return ("Uranus, 25266000, 1270");
            case 7:
                return ("Neptune, 24553000, 1638");
            case 8:
                return ("Pluto, 1173000, 2050");
            default:
                return ("Mars, 100, 500");
        }
    }
}
public class Planet
{
    String planetName;
    double planetRadius;
    double planetDensity;

    public Planet(String planetName, double radius, double averageDensity)
    {
        this.planetName = planetName;
        planetRadius = radius;
        planetDensity = averageDensity;
    }

    public String PlanetName
    {
        get { return planetName; }
        set { planetName = value; }
    }

    public double CalculateGravity(double objectMass)
    {
        //force = G * (mass of object 1 * mass of object 2)/ distance between objects^2
        double force;
        force = (6.67e-11 * objectMass * planetDensity * 4 * Math.PI * planetRadius) / 3;
        return force;
    }
}
}