All Smithsonian museums and the National Zoo are closed due to the federal government shutdown.
A new year is a good time to look at how people have marked the passage of days, months, and years. Calendar systems include solar and lunar calendars that guide planting and harvest as well as synchronized electronic appointment books that keep modern societies humming along. Perpetual calendars rely on cycles that repeat. Native Americans used winter counts to convey and hold information about important events of the year with images.