Mars and seasonal cycles of Mars are likewise similar to those of Earth, as is the tilt that produces the seasons. Mars is the site of Olympus Mons, the largest volcano and second-highest known mountain in the Solar System, and of Valles Marineris, one of the largest canyons in the Solar System. The smooth Borealis basin in the northern hemisphere covers 40% of the planet and may be a giant impact feature. Mars has two moons, Phobos and Deimos, which are small and irregularly shaped. These may be captured asteroids, similar to 5261 Eureka, a Mars trojan. There are ongoing investigations
Solar System in fiction Solar System in fiction The Solar System and its various bodies (planets, asteroids, moons, etc.) were the earliest objects to be treated as fictional locations in works of science fiction. Among these, imaginary voyages to and explorations of Earth's Moon are found in seventeenth century literature. By the early twentieth century, following the increase in scientific and technological development spurred by the Industrial Revolution, fictional journeys to (or from) the Solar System's other planets had become common in fiction. Early literature regarding the Solar System, following scientific speculations dating back to the 17th century, assumed that every planet hosted its