here is another idea for a horizon. file updates every 10 minutes.

it is made of a huge half-sphere inside of the google sky-view, slightly smaller than the projection-sphere for the sky images. unfortenuately it has some odds like flickering and parallax view errors - sometimes it even disappears

, and it is not as accurate as the heywhatsthat planisphere but I think it is ok for 'backyard' purposes.