size difference between mars and earth
Mars is only about one-half the diameter of Earth, but both planets have roughly the same amount of dry land surface area. This is because over two-thirds of the Earth's surface is covered by oceans, whereas the present surface of Mars has no liquid water. Mars and Earth are very different planets when it comes to temperature, size, and atmosphere, but geologic processes on the two planets are surprisingly similar. On Mars, we see volcanoes, canyons, and impact basins much like the ones we see on Earth.