Red Planet Day takes place on November 28, 2021. It commemorates the launch of the Mariner 4 spacecraft on November 28, 1964. Mariner 4 performed the first successful flyby of the planet Mars returning the first pictures of the Martian surface. It was designed to conduct closeup scientific observations of Mars and to transmit these observations to Earth.
Mars is the fourth planet from the Sun and the second smallest planet in the Solar System. Named after the Roman god of war, it is often described as the "Red Planet" because the iron oxide prevalent on its surface gives it a reddish appearance. Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the volcanoes, valleys, deserts, and polar ice caps of Earth.
The rotational period 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 second highest known mountain within the Solar System (the tallest on a planet), and of Valles Marineris, one of the largest canyons. Mars has two known moons, Phobos and Deimos, which are small and irregularly shaped. (With material from: Wikipedia)