Jazz   Jazz music, an art form original to the United States, originated in the southern city of New Orleans at the turn of the twentieth century. It combined the elements of ...

Erratics and Drift   In the nineteenth century, scientists theorized that glaciers (ice sheets) covered much of Earth's surface during an ancient very cold period known as the...

Mars's Disappearing Atmosphere   For about the first billion years of its life, Mars was probably a watery planet. There are signs of past water in surface features, such as d...

The Early Iron Age     During the Bronze Age (roughly 3300-1200 B.C.E. in the Middle East), civilizations were limited in their use of iron. Most iron occurred not in ...

重复时间 2024-06-18 2024-09-28 2025-02-22 Equestrian Portraits in the Eighteenth and Nineteenth Centuries     It was common for European rulers from the eighteenth ...

The Moon's Origin   One of the earliest scientific theories about the Moon's origin postulated that Earth and its moon formed out of a dust cloud alongside one another, much a...

The Origin of Mars's Moons     Mars has two tiny moons, Phobos and Deimos. The orbits of both these satellites are nearly circular and close to the planet: Phobos orbits...

Why Did Agriculture Arise   Sometime around 10,000 years ago, some hunter-gatherers took up agriculture. Though the advantages may seem obvious, there are also disadvantages: ...

Opera in Seventeenth-Century Venice     Opera, a form of drama set to music and featuring vocal performance supported by an orchestra, was born in Italy at the very end ...

  Periglacial Mounds   Periglacial regions are cold-climate areas that are located near the margins of glaciers-permanent ice sheets covering parts of the Arctic and ot...