Our Mr. Sun (1956) [SHORT]
Academy Award winner Frank Capra (IT HAPPENED ONE NIGHT, MR. SMITH GOES TO WASHINGTON) wrote and directed this children's documentary about the Sun. A mix of Animation and Live-Action, this Two-Part Short is barely an hour long, and is in the Public Domain. Lionel Barrymore (Mr. Potter of IT'S A WONDERFUL LIFE) lends his voice to Father Time.
And how about the other Frank Capra short, "The Unchained Goddess?" That was a fun one as well.