Like those charged with criminal contempt, the court may order incarceration of people held in civil contempt. However, unlike individuals charged with criminal contempt, people held in civil contempt are generally not given the same constitutional rights that are guaranteed to criminal contempt defendants.
On Saturday, June 12th the largest American and largest flag in the world was on display for one hour at Moffett Field in Mountain View California. This flag is 255 feet by 505 feet. It's by Ski Demski who had the Stars and Stripes unfolded on the Hoover Dam.
Let's assume that the stripes on the flag are 1.5 inches wide and we want to just be able to see them. Using the same method as above we can come up with an answer. In this case we need to be able to see something that is 1.5/12/5280 miles wide, or 2.367e-5 miles.