The moon is our close cosmic neighbor, and humans have been exploring its surface ever since they first developed telescopes.
The first lunar exploration vehicles of the 1950s were primitive pioneers. But aerospace technology developed so rapidly that only about a decade separated the first flyby forays and Neil Armstrong's history-making steps on the moon's surface.
In January 1959 a small Soviet sphere bristling with antennas, dubbed Luna 1, flew by the moon at a distance of some 3,725 miles (5,995 kilometers). Though Luna 1 did not impact the moon's surface, as was likely intended, its suite of scientific equipment revealed for the first time that the moon had no magnetic field. The craft also returned evidence of space phenomena, such as the steady flow of ionized plasma now known as solar wind.