Why do planetary scientists hypothesize that the moon formed with a molten surface

The oldest lunar rock samples are approximately 4.4 billion years old and composed of anorthosite, a mineral that crystallizes and rises to the top of a lava ocean.

an energy transformation flow diagram is shown

where is it ?

one "light year" is the distance that light travels, through vacuum, in one julian year.   that's 365.25 days, of 24 hours each.