PHILADELPHIA (CBS) — According to a new study, planet Earth is not just one planet. It is actually two planets.

This finding comes from a group of researchers led by Edward Young at UCLA. According to the study, Earth is a combination of what was originally Earth and another planet called Theia which collided with Earth billions of years ago.

The original theory was that Earth and Theia sideswiped each other 4.5 billion years ago. The theory said that the crash led to the formation of our planet’s moon.

The research team, funded by NASA, now believes that Theia and Earth did not just sideswipe each other. They say there was a head-on collision between the two heavenly bodies.

According to the study, Earth as we know it today, is actually two planets fused together as the collision resulted in Earth absorbing a chunk of Theia. It also suggests that the moon is part Theia as well.

The findings are based on oxygen isotopes being studied in rocks retrieved from the moon and rocks from Earth taken from the Earth’s mantle in Hawaii and Arizona.

Research found that the oxygen isotopes in rocks on the moon and Earth were indistinguishable.

“Had Earth and Theia collided in a glancing side blow, the vast majority of the moon would have been made mainly of Theia, and the Earth and moon should have different oxygen isotopes. A head-on collision, however, likely would have resulted in similar chemical composition of both Earth and the moon,” the findings read.

Researchers say that Theia did not survive the impact and was growing at the time of the collision — likely to become a planet of its own one day.

Instead, scientist believes it makes up large parts of the Earth we now live on and the moon.