Learn to tell the time by looking to the stars

Posted April 3, 2012

Does anyone use a watch anymore? Unless it’s a Rolex for show, it seems time keeping has migrated to mobile phones. Not that I miss the good old days. I enjoy how ingenious we are, constantly re-inventing and re-packaging old ideas.

Time-telling is as ancient as the stars. Planting, harvesting and important civil and religious ceremonies were tied to calendars based on the movements of the sun, planets and particular stars and star groups. If you’re in a retro mood and willing to extricate phone from palm, how about a mind-meld with the ancients the next clear night?

Before you go out, visit this site (http://bit.ly/HPTDa9) and make yourself a star clock. This simple device, which you can assemble from two pieces of paper, lets you tell time using the Big Dipper. Here is a direct link to the Adobe Reader PDF file to print out the star clock (http://bit.ly/HQwuFL).

You can treat the two Pointer stars at the end of the Dipper’s Bowl as an hour hand on a clock with the North Star at the center. As the Earth turns, the Big Dipper describes a circle around the North Star every 24 hours, or one rotation of the Earth. From the northern U.S., that circle never gets cut off by the horizon and so the Dipper never sets.

The star clock is a fun little project that even I could put together in under 10 minutes. It’s the lowest of low-tech and would make a fun exercise for the classroom. There’s even a paperless way that I’ll share Wednesday after I check out how it works tonight. Stay tuned.

King is the chief photographer at the Duluth News-Tribune and blogs about astronomy at astrobob.areavoices.com

Tags: diversions, science, astronomy