Main Scene and Game State - Learn SpriteBuilder for iOS Game Development - page 210

Figure 7-4 . A scary animation. Doesn't look like it. Doesn't look like much either, but it has its effect. It's
not shown here because you have to see it in motion
They should all be children of the centered background node so that the sprites will auto-
matically be centered on the layer. The sprites center automatically because the anchor
point for sprites defaults to 0.5x0.5, meaning the texture is drawn centered on the sprite's
position.
Note Changing a node's anchor point affects scale and rotate operations, as
well as bounding box and collision detection. The anchor point only shifts the
visual representation of a node, and this change may not be represented by, say,
physics. You should never mistake the anchor point as a way to position nodes.