Mars, Venus, and Mercury are the planets most like Earth. They’re spinning balls of rock.
Venus is about the same size as Earth. Mars has seasons and poles topped with ice, just like Earth. And they’re in our neighborhood, not far from the Sun. But the surface of Venus is hot enough to melt lead. Mars has dust storms as strong as hurricanes. Sunrise to sunrise on Mercury takes six Earth months. Scientists learn a lot about Earth by studying these planets. Looking at our neighbors is like asking over and over, “What if Earth were...?”
