In today's image, we see an ancient observatory in Beijing including a giant Armillary Sphere which can be used to measure positions of objects in the sky. The star trails in the sky show the motion of Earth as it rotates on its axis making the stars appear to move across the sky.

My podcasts are available in video form through this YouTube Channel.

This Podcast is an authorized New Media Mirror Site for APOD. You can access the image and website directly at: Astronomy Picture of the Day. You can use the archive link below the image to select the photo corresponding to the date of this podcast.

I welcome comments and suggestions about these podcasts. I can be reached here: wagnerastronomy@gmail.com

This work is licensed under a Creative Commons Attribution 4.0 International License.