International Date Line International Date Line The International Date Line (IDL) is an imaginary line of demarcation on the surface of Earth that runs from the North Pole to the South Pole and demarcates the change of one calendar day to the next. It passes through the middle of the Pacific Ocean, roughly following the 180° line of longitude but deviating to pass around some territories and island groups. The IDL is roughly based on the meridian of 180° longitude, roughly down the middle of the Pacific Ocean, and halfway around the world from the Greenwich meridian. In many places, the IDL follows
Malapert (crater) is overlain by what appear to be impact craters. There are also small craters overlying the southeastern rim. Much of the interior and details of the rim remain hidden by shadows. The southwestern part of the rim forms part of a 5-km-high rise in the surface that has been unofficially designated Malapert Mountain. This ridge appears wider along a line running roughly east–west, although details of the back side are hidden by shadows. The peak of this ridge lies almost exactly along 0° longitude, and it has the unusual attribute of lying within sight of both the Earth and the