Mars is about half the diameter of Earth, and takes almost 2 years to orbit the Sun. Its tilt and rotation period are similar to Earth's, so it experiences similar seasons as we do, but each season is twice as long. The big scar across the planet is a canyon system 3000km (almost 1900 miles) wide, which is about the distance from East Texas to the Pacific Ocean. It looks like a huge rock flew by and scraped Mars.