A trip to an ancient site like Chaco Canyon National Historic Park in New Mexico is a very rewarding experience. Scientists and Anthropologists have discovered the ancient inhabitants created predictors for the solstices and equinox by noting when the sun would rise or set behind features on the horizon. One of the most famous at Chaco Canyon is Anasazi Sun Dagger. Chaco Canyon has other features like doors, windows, and hallways that align with the Sun at certain times during the year. Chaco Canyon isn’t unique. In Great Britain places like Stonehenge and Avebury, or Ireland’s Newgrange and Egypt’s pyramids and Nabta Playa show alignments with astronomical objects.
Your task is to find a place where you live where on the winter or summer solstice you can view the rising or setting Sun behind an object on the horizon (how might your astrolabe be able to help with this activity?). Take a picture that shows the event.
While it would take much too long for the benefit, the same method could be used to find the length of a year. Here you would count the number of days until the sun came up behind the object again. If you keep observing you’ll note that after a few years your object won’t exactly be in front of the sun when it rises or sets. This is because a year is really more than 365 whole days long and that a leap-year correction needs to be made. Ancient societies had centuries to work this out and develop their calendars. Investigate ancient calendar systems some night when you can’t get out to observe and nothing is on TV.
Results
Finding a Stone Henge or Casa Grande in Broomfield, Colorado (click here)
Morning sunrise at the Solstice Casa and Iglesia (Church) Grande in Broomfield, Colorado (click here)
Evening sunset at the Broomfield Memorial Solstice Bench (click here)