Therefore, to put things into perspective, if you weigh 100 pounds on Earth then you would weigh only 38 pounds on Mars. Mars has two moons , Phobos and Deimos , which are small and irregularly shaped. Phobos (left) measuring 13.4×9.2 km (8.3×5.7 miles) and Deimos (right) at 7.5×5.2 km (4.7×3.2