Amateur astronomers have been awaiting the closest approach of Mars to the Earth since 2003. On July 27 the Earth-Mars distance was only 55 million kilometers. Unfortunately a major global dust storm enshrouded Mars for more than a month, preventing surface details from being observed. The dust storm began as a localized phenomenon in late May, but it grew incredibly quickly. By the third week of June, the storm had become a planet-circling event. The storm was finished at the beginning of September and after that the observation of Mars surface was clearest.
Comet 21P/Giacobini–Zinner