How did the Moon form? To help find out, NASA launched the twin Gravity Recovery and Interior Laboratory (GRAIL) satellites in 2011 to orbit and map the Moon's surface gravity in unprecedented detail.

What's that bright orange dot above the large telescope on the right? Even seasoned sky enthusiasts might ponder the origin of the orange orb seen by scrolling across this panoramic image, taken last December. Perhaps identifying known objects will help.

Why is Venus so different from Earth? To help find out, Japan launched the robotic Akatsuki spacecraft which entered orbit around Venus late in 2015 after an unplanned five-year adventure around the inner Solar System.