Raycast Hit Collider is Always NULL

Question

I am trying to detect if a user is grounded. I have a GameObject on the screen with a BoxCollider2D component on it and is on the Ground Layer. I then have a character with a Rigidbody2D and CircleCollider2D on it along with this class:

public class CharacterEnvironment : MonoBehaviour {

    float distToGround;

    // Use this for initialization
    void Start() {
        var collider = GetComponent<CircleCollider2D>();
        distToGround = collider.bounds.extents.y;
    }

    // Update is called once per frame
    void Update() {
        RaycastHit2D hit = Physics2D.Raycast(transform.position, Vector2.down, distToGround + 0.1f, LayerMask.NameToLayer("Ground"));
        Debug.Log(hit.collider);
        if (hit && hit.collider != null) {
            Debug.Log(hit.collider);
        }
    }
}

When my raycast runs, hit.collider is always null, even when the object is resting on top of the Ground Object. Am I doing the calculations wrong?

Edit: I have added the check for hit in the if statement.