Our galactic neighbourhood is middling peaceful these days . So peaceful , in fact , that it ’s well-fixed to forget its violent and spectacular beginnings . Fortunately , we have scientists to remind us . A paper published last week in the journalSciencereports that Earth once smashed into , then combine with , another major planet . They say the Moon formed out of the resulting wreckage too .
That planet ’s name was Theia . At the time of the hit , Theia was so untried that investigator refer to it as a “ erratic fertilized egg . ” Though it ’s crucial to note that Earth was only 100 million yr old itself — also young in cosmic time .
While knowledge of the planet ’ hit is n’t new , the paper ’s co - writer uncovered new details of the event . Most scientists believe the impact had occurred at a 45 - degree angle , like one car sideswiping another . But this new research shows it was probably more like a brutal head - on collision .
How can you be sure about something that happened to our planet most 4.5 billion years ago ? Take a skilful look at the Moon . Researchers tested lunar rock samples gather up by spaceman on the Apollo 12 , 15 , and 17 foreign mission . They also reckon at six volcanic rocks from Hawaii and Arizona . The scientist focalise on the rocks ’ chemical substance makeup — specifically on their oxygen molecule .
research worker Paul Warren , Edward Young and Issaku Kohl with a lunar month rock sample . Image quotation : Christelle Snow / UCLA
There are several isotope of O , each named for its telephone number of protons and neutrons . O-16 , which make up almost all of the atomic number 8 on Earth ( including in rocks ) , has eight protons and eight neutrons . We also have pocket-sized quantities of O-17 and O-18 . The ratio of these three isotopes acts as a chemical key signature , so if two entity have the same ratio , it ’s potential they ’re made of the same stuff .
The theory was that Theia ’s bump off - and - course impact cast out sherd of both planets outward into space , where gravitative force-out compressed them into a single ball : the Moon . If that ’s so , then the Moon ’s proportion of isotopes should look unlike from Earth ’s . And some scientist conceive that ’s the type .
But the investigator behind the new paper argue otherwise . " We do n’t see any difference between the Earth ’s and the moon ’s oxygen isotopes ; they ’re identical , " leash generator Edward Youngsaid in a public press release .
What does this mean ? It mean , the investigator say , that Theia hit Earthhardand fast , and likely straightaway - on . Some of the debris from Theia and Earth combined to form the planet we call home today , and some of it blend to form the Moon .
" Theia was thoroughly mixed into both the Earth and the Moon , and evenly dispersed between them , " Young order . " This explains why we do n’t see a dissimilar signature of Theia in the Moon versus the Earth . "
