For observers on Earth, the sun appears as a bright, familiar disk—but what we see is only half the story. Like the moon, one ...

The foes are trying to exert control over the narrow passageway. Most ships aren’t moving. Here’s what to know.

A compass used by Lewis and Clark on their expedition to explore the American West is owned by the Smithsonian and is part of NPR's 250th anniversary series, America In Pursuit.