I have what I thought was an easy problem. I want to make a small animation showing the Earth revolve around the Sun with lighting set up to show how the axial tilt causes the seasons. The Earth also rotates.
I can almost get there. The problem I'm having is when I try to tilt the Earth's rotational axis (the Z-axis) so it is not aligned with the global Z axis. As soon as I start the animation, it realigns. Here's what I'm doing.
I create an empty, then numpad-7 to get the x-y view. I set up two key-frames at 0 and 61 to go through a full 360-degree rotation. This rotates very nicely with a second period (targeted at NTSC). I can view the rotation using any of the 3-d views.
I then do a numpad-1 to get the x-z view. I rotate the empty's z axis by about 20-25 degrees (just by hand). It looks fine, but as soon as it hit the play button, the empty's axis realigns with the global z axis and then it rotates.
What I am doing wrong?