Extraterrestrial skies Mars appears to be the angular diameter as seen from Earth (0.35°), and sends 40% of the light, approximately the brightness of a slightly cloudy afternoon on Earth. On June 3, 2014, the "Curiosity" rover on Mars observed the planet Mercury transiting the Sun, marking the first time a planetary transit has been observed from a celestial body besides Earth. Mars has two small moons: Phobos and Deimos. From the Martian surface, Phobos has one-third to one-half the angular diameter of the Sun while Deimos is barely more than a dot (only 2′ angular diameter). The orbital period of Phobos
NASA Human Exploration Rover Challenge NASA Human Exploration Rover Challenge The NASA Human Exploration Rover Challenge, prior to 2014 referred to as the Great Moonbuggy Race, is an annual competition for high school and college students to design, build, and race human-powered, collapsible vehicles over simulated lunar/Martian terrain. NASA sponsors the competition, first held in 1994, and, since 1996, the U.S. Space & Rocket Center hosts. Students created vehicles dubbed "moonbuggies" to face challenges similar to those engineers at NASA's Marshall Space Flight Center addressed in preparation for Apollo 15. On that mission, on July 31, 1971, the first Lunar Roving Vehicle extended the range