Theia, a theoretical ancient planet about the size of Mars, is believed to have collided with Earth during its infancy, triggering debris that collected to later form the moon. However, contrary to popular belief, no remnants of Theia contributed to forming the moon and instead the lunar satellite is likely only made of material ejected from Earth because of the collision.

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A new study suggests that Theia had little to do with the Moon taking shape and no parts of the ancient planet exist in the Moon's composition. A BBC report, citing the study, says that the debris that formed the moon only comprised material from Earth and nothing from Theia.

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Theia is believed to exist in Earth's core to date.

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Is Moon all Earth? 

Scientists studied 14 lunar rock samples and similar minerals from Earth. They compared the two and measured them for levels of oxygen-17, a rare isotope of oxygen. They found strikingly similar levels of the component in both sets of samples, thus deducing that the point of origin for both Earth and the Moon was the same. 

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Since there was no other external material in the picture, they believe that the material ejected from Earth because of the collision with Theia, came together over several years to form the Moon as we know it today. Meanwhile, nothing from Theia contributed to its structure.

Andreas Pack from Göttingen University, a part of the team of scientists that conducted the study, said, "One explanation is that Theia lost its rocky mantle in earlier collisions and then slammed into the early Earth like a metallic cannonball."

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Theia lies inside Earth?

He added that if this had happened, then Theia "would be part of Earth’s core today, and the Moon would have formed from ejected material from Earth’s mantle."

Meanwhile, the scientists also took a dive into the source of water on Earth. Theia is believed to have brought water to the planet, but that is only a theory. The study suggests that water was brought to Earth most likely by asteroids that collided with the planet long after the Moon was formed.

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A class of meteorites called enstatite chondrites could have brought water to Earth since the study found similar levels of oxygen-17 in the composition of these meteorites and the samples from Earth.

Theia has long fascinated scientists and it is also theorised to be the reason for the formation of continents on Earth and even impacted volcanic activity.