快猫短视频

THE 鈥渟uicide note鈥� left behind by a space probe has presented astronomers
with a puzzle: where did Jupiter come from? The dying breaths of the Galileo
atmospheric probe hint that the planet might have wandered towards the Sun after
forming on the fringes of the Solar System.

In 1995, the Galileo mission dropped a probe into the Jovian atmosphere. A
mass spectrometer on board returned data on the composition of the atmosphere
before the probe was crushed by pressures of 20 atmospheres.

If Jupiter had formed from colliding comets, as many planetary physicists
believe, then the levels of argon and other volatile elements in its atmosphere
should be roughly the same as those observed in comets. However, the probe
measurements reveal that they are not the same, says Tobias Owen, a physicist at
the University of Hawaii. 鈥淎rgon is as abundant relative to hydrogen as carbon
and sulphur,鈥� he says. 鈥淚t was expected to be much less abundant.鈥� Krypton and
xenon, too, are present at higher levels than expected.

鈥淭he pattern in the Jupiter data is not what is seen in comets,鈥� agrees Kevin
Zahnle of NASA鈥檚 Ames Research Center in Moffett Field, California. 鈥淚t鈥檚 very
interesting, because it was thought that comets were the building blocks.鈥�
Although Zahnle admits that the data analysis is very difficult and potentially
error-prone, he says that if the findings are correct, the implications are
important.

One possibility is that Jupiter formed in a cold region much farther away
from the Sun, allowing the young planet to trap volatile gases. The planet may
then have migrated inwards to its current position. Another possibility is that
Jupiter formed from material that was more primitive than anyone realised. Owen
says: 鈥淚t looks as if we鈥檙e dealing with something even more primordial than
肠辞尘别迟蝉.鈥�