Researchers analyzing samples returned by NASA's Genesis mission say that the sun and the solar system's inner planets, including the Earth, may have formed differently than previously thought.
The data from Genesis, which collected material from the solar wind blowing from the sun, reveal differences between the sun and planets with regard to oxygen and nitrogen, two of the most abundant elements in our solar system — a difference that could help determine how our solar system evolved.
On Earth, the air contains three kinds, or isotopes, of oxygen atoms, which differ in the number of neutrons they contain.
Genesis co-investigator and UCLA professor of Earth and space sciences Kevin McKeegan and his colleagues measured, for the first time, the isotopic composition of oxygen in the solar wind. They found that the sun has about 6 percent more O-16 — relative to both of the minor oxygen isotopes — than the Earth does.
The data were obtained from an analysis of material ejected from the outer portion of the sun.
"We found that the Earth and 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," McKeegan said.
"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,” he added.
That material gathered by Genesis can be thought of as a fossil of our nebula because scientific evidence suggests that the sun''s outer layer has not changed measurably in billions of years, the researchers said.
The study has been published in the journal Science.