Inner planets did not form from the same material as the sun

Artist's rendering of the Genesis Spacecraft during the Collection Phase of Mission with the Sun. Image courtesy of NASA/JPL-Caltech

Solar nebulae ‘fossils’ suggest that the sun and the inner planets did not form from the same materials, according to researchers.

Samples taken during NASA’s 2004 Genesis Mission has found differences in the chemical makeup of the inner planets and the sun. Researchers from NASA’s Jet Propulsion Laboratory say the data revealed different concentrations of oxygen and nitrogen, two of the most abundant elements in our solar system.

These slight differences could provide a clue to how our solar system formed. Genesis co-investigator Kevin McKeegan, UCLA, said in the press release “We found that Earth, the moon, as well as Martian and other meteorites which are samples of asteroids, have a lower concentration of the O-16 than does the sun.”

“The implication is that we did not form out of the same solar nebula materials that created the sun- just how and why remains to be discovered.”

Genesis spent 886 days at Earth’s L1 Lagrange Point- approximately 1 million miles from Earth- between 2001 and 2004, passively collecting solar wind samples, or material ejected from the outer portion of our sun. In 2004 it launched a return capsule containing the samples.

Scientific evidence suggests that the outer layer of the sun has not changed for billions of years, so the samples are fossils of the solar nebula that created it. Genesis Principal Investigator Don Burnett, the California Institute of Technology, said “The sun houses more than 99 percent of the material currently in our solar system, so it’s a good idea to get to know it better.”

Earth’s air contains three isotopes of oxygen- O-16 (the most abundant), 0-17 and 0-18. The Genesis samples revealed that the sun had a higher concentration of O-16 than Earth, while the concentrations of O-17 and O-18 were lower than on the terrestrial planets.

There are also different isotopes for nitrogen- the more common N-14 and the rare N-15. Jupiter and the sun both have higher levels of N-14, but the levels of N-15 were 40 per cent lower than the levels on Earth.

Genesis co-investigator Bernard Marty, Centre de Recherches Pétrographiques et Géochimiques, said “These findings show that all solar system objects including the terrestrial planets, meteorites and comets are anomalous compared to the initial composition of the nebula from which the solar system formed.

“Understanding the cause of such a heterogeneity will impact our view on the formation of the solar system.”

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