National Geographic recently published Rewind the Red Planet, an interactive feature that demonstrates how the landscape of Mars has changed over the past 3.8 billion years. As this feature demonstrates, scientists aren't entirely sure what Mars looked like 3.8 billion years ago. Some evidence suggests that Mars featured crater lakes and possibly even an ocean. Other evidence, however, suggests that Mars was once a glacial planet. As visitors scroll through this webpage, they will see artistic renderings of Mars and its different features throughout time. Each image is accompanied by a short description that describes the events and phenomena that changed this planet over billions of years.