Mission suggests Sun and planets constructed differently
Although the differences in oxygen and nitrogen are slight, the implications could help determine how our solar system evolved.
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NASA/JPL —
Published:
June 24, 2011 Artist rendering of the Genesis spacecraft during collection phase of mission. NASA/JPL-Caltech
Data revealed differences between the Sun and planets in oxygen and nitrogen, which are two of the most abundant elements in our solar system. Although the difference is slight, the implications could help determine how our solar system evolved.
“We found that Earth, the Moon, as well as martian and other meteorites, which are samples of asteroids, have a lower concentration of O-16 than does the Sun,” said Kevin McKeegan from the University of California, Los Angeles. “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.”
The air on Earth contains three different kinds of oxygen atoms, which are differentiated by the number of neutrons they contain. Nearly 100 percent of oxygen atoms in the solar system are composed of O-16, but there are also tiny amounts of more exotic oxygen isotopes called O-17 and O-18. Researchers studying the oxygen of Genesis samples found that the percentage of O-16 in the Sun is slightly higher than on Earth or on other terrestrial planets. The other isotopes’ percentages were slightly lower.
Another study detailed differences between the Sun and planets in the element nitrogen. Like oxygen, nitrogen has one isotope, N-14, that makes up nearly 100 percent of the atoms in the solar system, but there is also a tiny amount of N-15. Researchers studying the same samples saw that when compared to Earth’s atmosphere, nitrogen in the Sun and Jupiter has slightly more N-14, but 40 percent less N-15. Both the Sun and Jupiter appear to have the same nitrogen composition. As is the case for oxygen, Earth and the rest of the inner solar system are different in nitrogen.
“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,” said Bernard Marty from the Research Center of Petrographics and Geochemicals in France. “Understanding the cause of such a heterogeneity will impact our view on the formation of the solar system.”
Data was obtained from analysis of samples that Genesis collected from the solar wind or material ejected from the outer portion of the Sun.
This material can be thought of as a fossil of our nebula because the preponderance of scientific evidence suggests that the outer layer of our Sun has not changed measurably for billions of years.
“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,” said Don Burnett from the California Institute of Technology in Pasadena. “While it was more challenging than expected, we have answered some important questions, and like all successful missions, generated plenty more.”
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