Last time we learned about Mars' great Valles Marineris, the largest canyon in the solar system. But what about here on Earth, is the Grand Canyon really the biggest?

There are alot of great caves in the US but there is a hot debate over which one is better Mammoth Cave or Carlsbad Caverns.

Ryan Crow of the U.S. Geological Survey (USGS) gave a talk to a packed crowd at the Museum of Northern Arizona Jan. 12 ...

Welcome to Nat Geo Your Shot: National Geographic’s global community for aspiring visual storytellers. Find the community on Instagram @NatGeoYourShot and follow along for hashtag challenges ...

US President Donald Trump announced plans to build a domestic version of Israel’s Iron Dome missile defence system. This new project will aim to protect the US from various missile threats.