Mars has captivated humans since we first set eyes on it as a star-like object in the night sky. Early on, its reddish hue set the planet apart from its shimmering siblings, each compelling in its own way, but none other tracing a ruddy arc through Earth’s heavens. Then, in the late 1800s, telescopes first revealed a surface full of intriguing features—patterns and landforms that scientists at first wrongly ascribed to a bustling Martian civilization. Now, we know there are no artificial constructions on Mars. But we’ve also learned that, until 3.5 billion years ago, the dry, toxic planet we see today might have once been as habitable as Earth.

- Science
- Explainer
Why we explore Mars—and what decades of missions have revealed
In the 1960s, humans set out to discover what the red planet has to teach us. Now, NASA is hoping to land the first humans on Mars by the 2030s.
Photograph courtesy NASA/JPL
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