Iardene Saese, of Port Chalmers School, asks :-
Andrew Lord, of Musselburgh School, asked:- Pippa Childs, of Cashmere Primary School, asked:-
What is the Moon made of?
Donald Wise, former Chief Scientist of NASA's Apollo Lunar Exploration Office, responded.
25 years ago the U.S. Apollo program started to bring back rock samples from the moon and yield answers to your question, one which has puzzled humans for thousands of years.
The moon has a composition remarkably similar to the earth's mantle, a zone which extends from a depth of about 35 km under the continents down to about 2900 km, where the earth's nickel-iron core begins. Both our mantle and the moon are composed largely of the elements silicon, oxygen, magnesium, iron and calcium. Just as on earth, these elements combine to form many different minerals and rock types.
Soon after the moon formed, its surface was melted into a 'sea' of molten rock, in part by the energy released from millions of meteorites of the early solar system pounding into its surface. As this molten sea cooled, mineral crystals began to form. The lightest was the mineral feldspar which floated upwards to collect as a surface 'scum' to depths of 50-100 km, forming the present light coloured highlands of the moon. Giant meteorites punched a few holes in this highland crust to create what some now call the 'eyes' of the 'man in the moon'. Continued deep melting was still able to produce lavas which flowed out over the basins to form the dark plains, features that the old astronomers called seas in the mistaken belief that they were oceans. These lavas are almost identical to earth's basalt, a rock produced when parts of our mantle are melted in volcanos.
Measurements of radioactive decay of the moon rocks showed that the moon, like the earth, was 4.5 billion years old and that almost all internal activity on it stopped about 3.2 billion years ago. Since then it has been a nearly dead world recording mostly the occasional impact of a meteorite. However its birth may have been a different story. The similiarity in composition to the earth's mantle is so great that most theories for its origin have it being born from the earth soon after formation of the earth's core. Lunar scientists are still debating just how this took place.