Jupiter's Great Red Spot is a storm like nothing this world
has ever seen. This crimson-hued anticyclone features winds three times as fast
as the jet stream and is big enough to swallow Earth whole. It is almost surely
older than any living human - 187 years at least - and could well still rage
across the gas giant's surface after all of us are gone. Scientists don't know
what makes the Great Red Spot so long-lasting. Nor can they explain the
chemistry behind its brilliant colour. But thanks to NASA's Juno spacecraft,
now on its second year of orbiting Jupiter, they know that the storm's roots go
deep: The well of hot, swirling gas that powers the Great Red Spot extends some
217 miles (350 km) into Jupiter's interior. The finding was announced Monday at
the annual meeting of the American Geophysical Union, along with other results
from Juno's first eight flights past the solar system's largest planet. The
spacecraft arrived in orbit around Jupiter in summer 2016 and has since
performed looping orbits that take it skimming between Jupiter's cloud tops and
radiation belts once every 53 days. On Earth, the Great Red Spot would almost
graze the orbit of the International Space Station. The highest clouds of our
planet's worst hurricanes top out at around 10 miles (16 km).
But understanding the behaviour of the Great Red Spot could
improve scientists' understanding of weather on Earth, said California
Institute of Technology planetary scientist Andy Ingersoll, a co-investigator
for the Juno spacecraft.
He called Jupiter's giant storm a good "stress
test" for Earth-based weather models.
It isn't clear what the new find means for the future of the
storm - Ingersoll said the spot already has stretched traditional weather
models to their limits.
But the spot has been shrinking steadily since the Voyager 2
spacecraft visited it in 1979; it used to be big enough to engulf two Earths.
High above the cloud tops, Jupiter is enveloped in radiation
belts formed by charged particles that get trapped by the planet's magnetic
field.
On Monday, scientists said that Juno had discovered a new
area of radiation just above the planet's atmosphere at the equator.The high
energy particles in this region are even more intense than those that make up
the radiation belt. But none of the eight spacecraft that preceded Juno at
Jupiter had spotted it. Juno's orbit meant "we literally flew through
it," said Heidi Becker, a physicist at NASA's Jet Propulsion Laboratory
who leads Juno's radiation investigation team. The radiation in this region is
thought to stem from fast-moving atoms of hydrogen, oxygen and sulfur. These
particles are produced in the gas clouds around Jupiter's moons, Io and Europa,
but are stripped of electrons and become charged as they interact with
Jupiter's atmosphere. The spacecraft found another area of high-energy
particles in Jupiter's inner radiation belt, where electrons move at nearly the
speed of light. Becker and her colleagues are still studying the exact nature
of these particles. Juno's other discoveries at Jupiter include clusters of
600-mile-wide cyclones at the planet's poles and an uneven magnetic field that
is weak in some places, but in others is 10 times as strong as anything found
on Earth.The spacecraft's high resolution camera has also taken thousands of
detailed images, revealing a planet that looks like a cross between a Van Gogh
painting and the world's most elaborate latte foam art. In a lecture, project
scientist Scott Bolton pulled up one of Juno's images of Jupiter's blue-tinged
polar storms and burnt sienna gas clouds. "If you had shown us that five
years ago, we couldn't have guessed what planet it was," he said.
SOURCE : The Washington Post
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