New to Java

Hello, I'm just learning to use enums at the moment. I've got this code below and was wondering what if the words in capital letters are java objects? I think they are, as I can use the dot operator on them in the main method, but in the code there is no Planet MERCURY = new Planet() etc.

public enum Planet 
{	
	MERCURY(3.03E23, 2.43E6),
	VENUS(4.68E24, 6.05E6),
	EARTH(5.96E24, 6.37E6),
	MARS(6.42E23, 3.39E6),
	JUPITER(1.9E27, 7.14E7),
	SATURN(5.68E26, 6.02E7),
	URANUS(8.68E25, 2.55E7),
	NEPTUNE(1.02e26, 2.47E7);
	
	private final double mass;
	private final double radius;
	
	public static final double G=6.67e-11;
	
	private Planet(double mass, double radius)
	{
		this.mass=mass;
		this.radius=radius;
	}
	
	public double surfaceGravity()
	{
		return G*mass/(radius*radius);
	}
	
	public double surfaceWeight(double otherMass)
	{
		return otherMass*surfaceGravity();
	}
	public static void main (String [] args)
	{
	System.out.println(JUPITER.radius);
	System.out.println(EARTH.mass);
	System.out.println(MERCURY.surfaceGravity());
	System.out.println(NEPTUNE.surfaceGravity());
	}
}