Tags: Crater.
Hun Kal is a small crater on Mercury that serves as the reference point for the planet’s system of longitude. The longitude of Hun Kal’s center is defined as being 20° W thus establishing the planet’s prime meridian.Hun Kal was chosen as a reference point since the actual prime meridian was in shadow when Mariner 10 photographed the region hiding any features near 0° longitude from view.Hun Kal is about 1.5 km in diameter.The name Hun Kal means ’20’ in the language of the Maya.
