26 meteorites give us new information on the birth of the Earth and the moon

10. April 2018

In a new study recently published in Nature, researchers from STARPLAN explains how the connection between the planets’ different chemical composition and their respective size can provide new information on the creation of the Earth and the moon.

According to researchers’ theory, a rotating disk of gas and dust, called the “protoplanetary disk,” circled around the sun and was the base on which the planets were created. A lot of grit and pebbles gathered together and grew bigger and later formed into what we now know as the planets in our solar system. However, this theory also entails an unanswered question: why do the planets not have the same chemical composition if they are created from the same material?

A new research study undertaken by head of center Martin Bizzarro and his colleague Martin Schiller, from the Center for Star and Planet Formation (STARPLAN) at the Natural History Museum of Denmark at the University of Copenhagen, offers a potential answer. According to Bizzarro and Schiller’s theory, the explanation is that the planets were created at different periods of time in the age of the protoplanetary disk.

”Through the age of the protoplanetary disk, grit was constantly added from the outer solar system. So, by looking at the consistency of the middle of the disk, one can see how it changes continuously as new material enters from the outside,” Schiller said to videnskab.dk. He added:

”That is why the celestial bodies have different compositions, depending on which time period they were developed.”

The researchers’ new theory on the creation of the planets is based on an analysis of 26 small meteorites from the solar system’s different rock-planets to examine the chemical composition of the planets’ calcium isotopes. These compositions constitute a sort of “isotopic fingerprint” that can reveal the planets’ weight and size and indicate the time of their creation – a connection that can also give us new information on when the creation of the Earth and moon took place.

According to Bizzarro and Schiller’s research results, the answer to the unsolved problem is that the planets were created at different times, which, according to the researchers, explains why the planets have different compositions.

”This knowledge gives us information on the time for the creation of the Earth and the moon. From our new isotopic fingerprints, we can conclude that the material from which the Earth and the moon were created must have been created at the end of the life of the protoplanetary disc, which means approximately 5 million years after the sun was created and shortly before the protoplanetary disc evaporated,” Professor Bizzarro explained to the University of Copenhagen.

Read more about the research result in Nature here

Further reading on STARPLAN and their research can be found here.