article_snippet.sent: About 4.45 billion years ago, 150 million years after the solar system formed, Earth was hit by a Mars-size object called Theia.
article_snippet.sent: Three studies have provided different theories for what happened after Earth was struck by a Mars-sized object called Theia, 4.45 billion years ago.
article_snippet.sent: What is agreed on, though, is that the impact actually happened (artist's illustration shown).
article_snippet.sent: This cloud would have been composed of some Earth material, explaining the similarity between Earth and The moon formed when a Mars-sized body called Theia, and other material.
article_snippet.sent: We still need to work out the details, but it's clear that We early solar system was a very violent place,’ added Dr Walker.
article_snippet.sent: The team said The team theory largely rules out the idea that the Mars-sized body Theia was of similar composition, or that the moon formed from only material contained in the pre-impact Earth.
article_snippet.sent: The other studies, though, disagree.
article_snippet.sent: Shown is an artist's illustration of the young Earth and moon .
article_snippet.sent: Whichever theory turns out to be correct though, the compositions of giant impactors are in agreement that the formation of the moon remains a confusing mystery that is yet to be fully solved.
article_snippet.sent: This is interesting stuff and no one has all the answers regarding the formation of the moon - we certainly don't claim to,’ Dr Walker, one of the authors of the former study, told MailOnline.
highlights_snippet.sent: University of Maryland researchers say cloud of debris rained on worlds .
  
highlights_snippet.sent: But Israel Institute of Technology says impactor was similar to Earth .