When Luke and C3P0 run outside to look for R2D2, the sky is a blushish purple. After Luke looks through his binoculars, there is a shot of him and C3P0, the sky is a redish purple. Then Owen tells Luke he's turning the power off, the shot changes, and sky is back to its orginal color. Note: I found this in the orginal version. I haven't seen the special edition yet so I don't know if it in that version too.