Earth

A fingerprint of Earth from space

Earth seen from orbit. Photo: NASA

Scientists have developed a fingerprint of Earth from space that could one day help identify other habitable worlds light-years from our own.

Why it matters: If researchers find a planet that matched Earth's fingerprint — which shows what Earth would look like in infrared if seen by an alien civilization — out there in the universe, it could indicate they've found a habitable world.

History, led by the forces all around us

In the East Africa Rift, Ethiopia. Photo: Eric Lafforgue/Art in All of Us/Corbis/Getty

Some six millennia ago, temperatures abruptly plunged, and a profound drought ensued in the then-tropical Middle East: To survive, people abandoned their land, migrated, and ultimately organized into a string of cities, stewarded over by strong rulers including the pharaohs in Egypt.

Quick take: Today, geopolitics usually mean war, human ego, big economics, or disease. But the Middle East drama in the third and fourth millennia BC illustrates the much-underestimated role of earthly forces in shaping and utterly turning history — and is a window into what may be in store for current and future generations.