Mysterious large mass

[guohua]

Update.

Mysterious large mass discovered on Moon bewilders scientists: 'Whatever it is, wherever it came from'

What is it? Evidence of an Old Underground Base or how about the Outer Shell of the Moon which is Hollow!~!

At roughly 1,550 miles in diameter, the Lunar South Pole-Aitken basin stretches across approximately one-fourth of the Moon, according to NASA. The Moon's circumference is roughly 11,000 kilometers.

They are saying this Depression was made by an Asteroid and it's a Crater.

In addition to being the largest crater on the Moon, the Pole-Aitken basin is also one of the largest known impact craters in the solar system and is thought to be approximately 4 billion years old.

 
Now doesn't make sense that an Asteroid of Iron That Large would have Demolished our Moon when it it.

James and his team looked at data from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission and the changes in gravity they discovered surprised them.


"When we combined that with lunar topography data from the Lunar Reconnaissance Orbiter, we discovered the unexpectedly large amount of mass hundreds of miles underneath the South Pole-Aitken basin," James said.
"One of the explanations of this extra mass is that the metal from the asteroid that formed this crater is still embedded in the Moon's mantle."

The anomaly – "whatever it is, wherever it came from," James added – is weighing down the basin floor by more than half a mile. The team of researchers ran computer simulations that show the iron-nickel core of an asteroid could have been placed into the upper mantle of the Moon following impact.
Source

 
Who here can explain to me how an asteroid that large impacted our moon and it is still there in our sky or maybe I don't understand Really How Big This Thing Was.