Mystery Unlocked: Moon's Tilt Could be Caused by Violent Vaporizing Impact

A new study published in the journal Nature reveals that the mysterious tilt on the moon's orbit could be caused by an angled impact millions of years ago. The giant impact vaporized most of ancient Earth, and have resulted to the creation of the moon.

For years, scientists have been baffled why the moon has a tilted orbit compared to Earth. To note, most orbits of major planets in the solar system lie within a thin, flat zone that follows the Sun's equator. This alignment to the Sun's equator is mainly due to the planets coming from a protoplanetray disk of gas.

Because of this, scientists uncover the moon originated to know why its orbit, as it revolves around the Sun, is tilted by about 5 degrees than most of the bodies in the solar system.

Past researchers say that early Earth's companion was not the moon but a Mars-sized rock called Theia. The early earth collided into Theia, creating the moon. But new research suggests that the present moon is actually from Earth and not from Theia.

Scientists reveal that the Earth and the moon have the same isotopic composition, which means that the giant impact was so strong that it vaporized Theia and most of the Earth. The dense vapor from the impact formed a cloud 500 times bigger than present Earth. The cloud consisted of materials from Earth and Theia, which cooled down and formed the moon.

"The inclination of the moon's orbit has been a major unsolved problem with the Earth-moon system. With a giant impact, the moon forms from a disk around the moon's equator, and even though the dynamical evolution of the system is complicated, if the moon started near the Earth's equator, we expect that it should stay near the Earth's equator as it moves away from the Earth over time — but we instead see this 5-degree inclination," Sarah Stewart, a planetary scientist at the University of California, Davis and a senior author of the new study, told Space.com.

"What's beautiful about this work is that we can end up with the current state of the moon — its orbit, its chemistry — with just one step, without invoking any other event. We don't invoke a sequence of events that needs to be just right to explain the moon's current state," she added.