This isn't new, but, as we debate how and when to go back to the Moon, it's important to understand what those brief trips 40 years ago taught us.
See the title link for the NASM site's details on all these discoveries.
The Moon is not a primordial object; it is an evolved terrestrial planet with internal zoning similar to that of Earth.
The Moon is ancient and still preserves an early history (the first billion years) that must be common to all terrestrial planets.
The youngest Moon rocks are virtually as old as the oldest Earth rocks. The earliest processes and events that probably affected both planetary bodies can now only be found on the Moon.
The Moon and Earth are genetically related and formed from different proportions of a common reservoir of materials.
The Moon is lifeless; it contains no living organisms, fossils, or native organic compounds.
All Moon rocks originated through high-temperature processes with little or no involvement with water. They are roughly divisible into three types: basalts, anorthosites, and breccias.
Early in its history, the Moon was melted to great depths to form a "magma ocean." The lunar highlands contain the remnants of early, low density rocks that floated to the surface of the magma ocean.
The lunar magma ocean was followed by a series of huge asteroid impacts that created basins which were later filled by lava flows.
The Moon is slightly asymmetrical in bulk form, possibly as a consequence of its evolution under Earth's gravitational influence. Its crust is thicker on the far side, while most volcanic basins -- and unusual mass concentrations -- occur on the near side.
The surface of the Moon is covered by a rubble pile of rock fragments and dust, called the lunar regolith, that contains a unique radiation history of the Sun which is of importance to understanding climate changes on Earth.
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