Mid-May: See all four of the rocky, inner planets of our solar system at the same time. May 26: Watch for a total lunar eclipse during the second supermoon of 2021. Beginning mid-May, if you can find a clear view toward the western horizon, you'll have an opportunity to see all four of the rocky, inner planets of our solar system at the same time, with your own eyes. See all four inner planets (including Earth!) after sunset, beginning mid-May. Credit: NASA/JPL-Caltech Starting around May 14th, cast your gaze to the west about half an hour after sunset, local time to see if you can spot Mercury, Venus, and Mars. (And well, Earth is kind of hard to miss.)