non-static member error

using UnityEngine;
using System.Collections;

public class SpaceShipController : MonoBehaviour {

public float speed;

void FixedUpdate()
{
	float moveHorizontal = Input.GetAxis ("Horizontal");
	float moveVertical = Input.GetAxis ("Vertical");

	Vector3 movement = new Vector3 (moveHorizontal,0.0f,moveVertical);

	Rigidbody.velocity = movement; 
}

}

This is my code and i have been having some issues with it, the same thing happened when i wanted to do a scrolling background the other day and i dont know how to fix it because i dont understand the problem. " An object reference is required to access non-static member `UnityEngine.Rigidbody.velocity’" this code is for a top down bullet hell type of game.

Looks like you got it working, but to answer your question so you know why…

Rigidbody is a class identifier - it is not an object, but it defines what fields and methods a Rigidbody object has - it describes the object. To use object fields on it you must have an object instance. This means your code or some other code has created an instance of the Rigidbody class. At this point it actually exists and you can reference the fields on it, such as velocity. In your case, the Rigidbody instance exists on your game object because it was added in Unity’s inspector. But you need to get access to that instance, which you can do using GetComponent as you discovered.

Given all of that, it’s also possible for a class to have “static” properties. These are fields and methods that can be used without and instance of the class.

Now for your error message: When you coded Rigidbody.velocity = movement, you were telling the compiler that you want to set the velocity property on the Rigidbody class. But you can only set static properties on a class and velocity isn’t static. So the error message is telling you that velocity is a property that requires an object instance.

Hope that clears things up for you a little.