Skip to content
Geolens

Glossary

417 words used in the labs.

Find a term from the labs, understand the process behind it, and see how it appears in the landscape. Each entry connects an explanation with a real observation and a model you can explore.

Term

International Date Line

The conventional boundary across which the civil calendar date changes, located broadly near 180 degrees longitude. Its course bends around countries and islands for practical reasons. It differs from the prime meridian, which defines zero longitude.

What to look for

Landsat 8, 6 June 2017: Big Diomede (the larger island, left) belongs to Russia and Little Diomede (right) to the US. The International Date Line passes through the water between them; it is a convention, not a visible physical feature.

Related labs

Graticule and coordinates →
Big and Little Diomede islands in the Bering Strait, between snow-covered Russia and Alaska, seen by Landsat 8.
Loading photograph

Explore further with USGS water glossary · USGS volcano glossary · NPS glacial geology · NASA Earth facts. Photograph acknowledgements are collected on the Image credits page.