The discovery of these gases in such high quantities at Jupiter raises
questions about how they got there. "In order to catch these gases, Jupiter
to trap them physically by condensation or freezing," Owen said. This process, he
said, requires extremely cold temperatures of about -240 degrees Celsius (-400 degrees Fahrenheit), colder than the surface of Pluto, the planet farthest from the
Sun. Planetesimals (small objects orbiting the Sun) in the Kuiper Belt beyond Pluto would be this cold, but Jupiter is more than six times closer to the Sun and
thus is much warmer. For this reason, Jupiter could not have been the site where
the three noble gases were originally trapped.
"This raises some intriguing possibilities," Owen said. "One
suggests that Jupiter was formed out in the area around the Kuiper Belt and was
dragged inward to its present location. Another possibility is that the solar nebula, a huge cloud of gas and dust from which our solar system formed, was much colder than scientists believe. A third hypothesis proposes that the solid
materials that brought these noble gases to Jupiter began forming in the original
huge, interstellar cloud of gas and dust even before it collapsed to form the solar
nebula. That would make these icy materials older and more primitive than we had expected."
"If either of the last two hypotheses turns out to be correct, it
that giant planets can form closer to their stars than current theories predict,"
Owen said. "This could help explain the new observations of planetary systems around other stars, in which such close-in giant planets are relatively common."