{"id":154697,"date":"2025-11-26T23:15:13","date_gmt":"2025-11-26T23:15:13","guid":{"rendered":"https:\/\/www.newsbeep.com\/il\/154697\/"},"modified":"2025-11-26T23:15:13","modified_gmt":"2025-11-26T23:15:13","slug":"before-their-big-smashup-theia-and-earth-were-neighbors","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/il\/154697\/","title":{"rendered":"Before their big smashup, Theia and Earth were neighbors"},"content":{"rendered":"

\"TheiaView larger<\/a>. | Theia and Earth collided about 4.5 billion years ago, as depicted in this artist\u2019s concept. The moon then formed out of the chaos. Image via Max Planck Institute for Solar System Research<\/a>\/ Mark A. Garlick.<\/p>\n

Theia was a young, still-forming planet like Earth in the early solar system. Where did it originate?
\nTheia and Earth experienced a massive collision about 4.5 billion years ago. The collision formed the moon and left traces of Theia in both the moon and Earth.
\nNew analysis of elements from that leftover material suggests that Theia originated closer to the sun in the inner solar system.<\/p>\n

Theia and Earth: Neighbors in the early inner solar system?<\/p>\n

The leading theory for how Earth got its moon is that the moon formed from a large rocky body \u2013 known as Theia \u2013 that collided with the early Earth<\/a> about 4.5 billion years ago. But where did Theia come from? A team of researchers, led by the Max Planck Institute for Solar System Research (MPS) in Germany and the University of Chicago, said<\/a> on November 20, 2025, that Theia likely originated closer to the sun than Earth. You could say that Theia and Earth were neighbors in the inner solar system before they smashed into each other.<\/p>\n

It still isn\u2019t known exactly how the collision occurred, but scientists said Theia was destroyed, with only traces of it<\/a> still existing in the Earth and moon today.<\/p>\n

The researchers published<\/a> their peer-reviewed<\/a> findings in the journal Science on November 20, 2025.<\/p>\n

A massive collision 4.5 billion years ago<\/p>\n

Around 4.5 billion years ago, a large rocky body collided with the young Earth. Scientists have named this body Theia. Earth\u2019s moon was born from that chaos. And while scientists are confident this happened, they are still trying to determine specific details, such as the size and composition of Theia and how the impact affected the young Earth.<\/p>\n

Theia itself was obliterated in the collision. But traces of it still remain in both Earth and the moon.<\/p>\n

By tracking the isotopic fingerprints of iron in lunar and terrestrial rocks, researchers trying to understand the origin of Theia, the Moon\u2019s mysterious progenitor, add evidence to the idea that it came from the inner Solar System. Learn more in Science: https:\/\/scim.ag\/4oULoBk <\/p>\n

\u2014 Science Magazine (@science.org)<\/a> 2025-11-20T20:07:03.462523537Z<\/a><\/p>\n

Isotopes provide clues<\/p>\n

In the new study, researchers searched for clues to Theia\u2019s composition and origin. They looked at the ratios of metal isotopes<\/a> in rocks from both Earth and the moon. Basically, isotopes are variants of the same element that differ only in the number of neutrons in their atomic nucleus. They have the same number of protons and electrons, but different numbers of neutrons. This means there are also differences in the weight of the isotopes. The researchers explained that isotopes likely varied in the early solar system. So elements in the distant outer solar system had different isotope ratios than ones near the sun, for example.<\/p>\n

The researchers were able to analyze the isotopes of iron in 15 rocks from Earth and six rocks from the moon with unprecedented precision. The moon rocks were those that the Apollo<\/a> missions had brought back to Earth. The results showed the isotope ratios of all the rocks were quite similar. This was not unexpected, based on previous tests of moon rocks.<\/p>\n

\"RotatingThis animation depicts the 2 continent-sized blobs deep inside Earth\u2019s mantle. Image via Cottaar and Lekic\/ LiveScience<\/a> (CC BY 4.0<\/a>).
\nReverse engineering Theia<\/p>\n

How could the researchers determine the nature of Theia? They used reverse engineering<\/a>, sort of. Reverse engineering uses deductive reasoning to try to understand how a device, process, system or piece of software works or accomplishes a task, with very little to no insight into exactly how it does so.<\/p>\n

In this case, researchers used the similar isotopes in Earth and lunar rocks. Working backward, they tried to determine what the composition and size of Theia \u2013 and the composition of early Earth \u2013 were at the time of the collision.<\/p>\n

To do so, they looked not only at the iron isotopes, but others as well. These included chromium, molybdenum and zirconium. This provided important clues as to how Earth and the moon ended up being the way they are today. As planetary scientist and geochemist Nicolas Dauphas<\/a> at the University of Chicago and the University of Hong Kong explained<\/a>:<\/p>\n

These elements have different affinities for metal and therefore partition into planetary mantles in different proportions; this is why gold is so rare and precious! They give us access to different phases of planetary formation.<\/p>\n

Iron and molybdenum were already present in Earth\u2019s core, long before the collision with Theia. Later, those elements became absent in the mantle. But today, there is iron in Earth\u2019s mantle. The researchers said this iron must have come from Theia. There is also zirconium, which didn\u2019t sink into the core but instead remained in the mantle, until today.<\/p>\n

\"ManNicolas Dauphas<\/a> is a planetary scientist and geochemist at the University of Chicago and the University of Hong Kong. He is one of the authors of the new paper about the origin of Theia. Image via University of Hong Kong<\/a>.
\nThe origin of Theia<\/p>\n

All of this tells us more about Theia itself, but what abut its origin? The early Earth contained material from various different types of smaller rocky bodies. This happened as debris such as asteroids and other planetesimals<\/a> \u2013 small rocky objects in the protoplanetary disks<\/a> of young stars \u2013 collided together to form the larger planets, including Earth. By comparing the material from the early Earth with current known kinds of meteorites and asteroids, scientists can determine where different kinds of the material came from. This is also true for the material suspected to have come from Theia.<\/p>\n

Analysis of the Theia material indicates it likely originated from closer to the sun than Earth. So Theia was essentially another rocky body like Earth, although maybe smaller. And it orbited closer to the sun, just as Venus and Mercury do today.<\/p>\n

And then, somehow, Theia and the early Earth ended up smashing into each other. This not only formed the moon, but changed the course of Earth\u2019s own history as well.<\/p>\n

Bottom line: A new study suggests that Theia and Earth were neighbors in the early solar system about 4.5 billion years ago. Then their epic collision destroyed young Theia.<\/p>\n

Source: The moon-forming impactor Theia originated from the inner solar system<\/a><\/p>\n

Via Max Planck Institute for Solar System Research<\/a><\/p>\n

Read more: Are 2 huge blobs inside Earth due to an ancient impact?<\/a><\/p>\n

Read more: Collision may have formed the moon in only hours<\/a><\/p>\n

Paul Scott Anderson
\n View Articles<\/a><\/p>\n

About the Author:<\/p>\n

Paul Scott Anderson has had a passion for space exploration that began when he was a child when he watched Carl Sagan\u2019s Cosmos. He studied English, writing, art and computer\/publication design in high school and college. He later started his blog The Meridiani Journal in 2005, which was later renamed Planetaria. He also later started the blog Fermi Paradoxica, about the search for life elsewhere in the universe.
\n
\nWhile interested in all aspects of space exploration, his primary passion is planetary science and SETI. In 2011, he started writing about space on a freelance basis with Universe Today. He has also written for SpaceFlight Insider and AmericaSpace and has also been published in The Mars Quarterly. He also did some supplementary writing for the iOS app Exoplanet.
\n
\nHe has been writing for EarthSky since 2018, and also assists with proofing and social media.<\/p>\n","protected":false},"excerpt":{"rendered":"View larger. | Theia and Earth collided about 4.5 billion years ago, as depicted in this artist\u2019s concept.…\n","protected":false},"author":2,"featured_media":154698,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[19554,85,46,8245,141,1951,145,93770],"class_list":{"0":"post-154697","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-space","8":"tag-geology","9":"tag-il","10":"tag-israel","11":"tag-moon","12":"tag-science","13":"tag-solar-system","14":"tag-space","15":"tag-theia-and-earth"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts\/154697","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/comments?post=154697"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts\/154697\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/media\/154698"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/media?parent=154697"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/categories?post=154697"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/tags?post=154697"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}