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
When We Left Earth: The NASA Missions When We Left Earth: The NASA Missions When We Left Earth: The NASA Missions (or NASA's Greatest Missions: When We Left Earth in the UK) is a Discovery Channel HD documentary miniseries consisting of six episodes documenting American human spaceflight, spanning from the first Mercury flights through the Gemini program to the Apollo moon landings, the Space Shuttle, and the construction of the International Space Station. It was created in association with NASA to commemorate the agency's fiftieth anniversary in 2008. It first aired on June 8, 2008, and concluded on June 22. Each airing consisted of two hour-long episodes.