Eartha

Eartha is the world's largest rotating and revolving globe, located within the headquarters of the DeLorme mapping corporation in Yarmouth, Maine. The globe weighs approximately 5,600 pounds (2,500 kg), and has a diameter of over 41 feet (12.5 m).

The globe was built with a scale of 1:1,000,000, on which one inch represents 16 miles (26 km), one millimeter represents one kilometer. As with most globes, it's mounted at a 23.5 degree angle, the same axial tilt as the Earth itself; thus the equator is diagonal to the floor. It uses a cantilever mount with two motors, and simulates one day's revolution and rotation every 18 minutes, though it is possible for the motors to fully rotate the globe in as little as one minute.

The globe was completed on July 23, 1998, and it uses a composite database built from satellite imagery, shaded relief, colored bathymetry, and information about road networks and urban areas. The database used to generate the surface images was approximately 140 gigabytes.

Eartha is contained in an atrium with several glass walls that allow it to be seen from outside of the building; it is readily visible from U.S. Route 1. At night, the globe is illuminated.

Eartha is constructed around a truss structure which is called Omni-Span, and consists of over 6000 pieces of aluminum tubing. This is covered by a skin of 792 map panels, each covering 8 degrees of latitude and 10 degrees of longitude, and attached to the trusses with a custom-designed system of hidden bolts.

The atrium containing Eartha is open to the public during business hours. There is an adjacent gift shop that carries various DeLorme and geography related products. The mounting equipment is in a large pit below floor level and is visible to visitors, but the stairway down is chained off to prevent public access. There are two balconies that allow visitors to more easily view the higher parts of the globe. Some offices within the building also have views overlooking Eartha.

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