Short answers, pulled from the story.
Humanity first set foot on another celestial body at Mare Tranquillitatis on the 20th of July 1969. Neil Armstrong and Buzz Aldrin landed their Apollo 11 Lunar Module Eagle at 20:18 UTC. The landing area received the official designation Statio Tranquillitatis following his announcement.
Astronomers Francesco Grimaldi and Giovanni Battista Riccioli named this feature in 1651. Their lunar map titled Almagestum novum assigned the designation Mare Tranquillitatis. Earlier proposals existed before this official naming convention took hold, including Michael van Langren's name Mare Belgicum in 1645.
The Moon's Mare Tranquillitatis holds basalt formed during the Upper Imbrian epoch. This rock type dates to an intermediate to young age group within that period. Surrounding mountains likely belong to the Lower Imbrian epoch instead.
Scientists attribute this unique shade to higher metal content in the underlying basaltic soil or rocks. Color processing extracts this hue clearly from multiple photographs taken by orbiters. The elevated metal concentration distinguishes this area from surrounding lunar terrain.
Ranger 8 deliberately crashed into the mare on the 20th of February 1965 and transmitted 7,137 close-range photographs during its final 23 minutes of operation. Surveyor 5 achieved a soft touchdown on the 11th of September 1967 after sending back 19,118 images. These robotic precursors gathered critical data about surface conditions for future human missions.