Apollo astronauts set up mirror arrays, or “retroreflectors,” on the Moon to accurately reflect laser light beamed at them from Earth with minimal scattering or diffusion. Retroreflectors are mirrors that reflect the incoming light back in the same incoming direction. Calculating the time required for the beams to bounce back allowed scientists to precisely measure…

Earth’s nearest neighboring body in the solar system is its Moon, yet to date humans have physically explored just 5% of its surface. It wasn’t until 2023 – building on Apollo-era data and more detailed studies made in 2011-2012 by NASA’s automated GRAIL (Gravity Recovery and Interior Laboratory) mission – that researchers conclusively determined that…