Why Does Jupiter Have A Red Spot?


Looks like Jupiter forgot to pack sunscreen… Hey guys, Amy here with you on DNews. Jupiter’s Great Red Spot is arguably the
gas giant’s most notable feature. The spot is actually massive, swirling storm twice
as wide as the Earth that astronomers have been tracking since the 1800s. And even though
its shrinking to the tune of 580 miles per year — astronomers suspect eddies feeding
into the storm are affecting its internal dynamics, turning it from an oval into a circle
— it’s still going strong. That giant storm, and the name Great Red Spot
suggests, is also, well, red. But not because Jupiter is blushing. It’s red because Jupiter
has a bit of a sun burn. Scientists used to think that the red in the
Great Red Spot was due to chemicals welling up in the region from below the visible cloud
layers. If this were the case, the whole storm would be red, not just the top. But new lab
tests suggest something different is going on. Jupiter’s atmosphere is composed almost
entirely of hydrogen and helium with a few traces of other gases thrown in. Though these
other gases only exist in a tiny percentage, their effects can be significant. Two of the trace gases in Jupiter’s atmosphere
are ammonia and acetylene. In lab tests, scientists exposed these gases to ultraviolet light to
simulate sunlight interacting with these gases in Jupiter’s atmosphere. The experiment
produced a reddish material and when the team compared this material’s spectroscopic signature
to that of the Great Red Spot as observed by Cassini’s Visible and Infrared Mapping
Spectrometer, they found it to be a pretty close match. The reddish material matched
a model of the Great Red Spot in which the red-colored material is confined to the uppermost
region of the giant storm. Scientists think that below this sun-scorched
redness, the storm is actually pretty bland, colour-wise; lots of whites and grays. But it’s not just composition of the clouds
that accounts for the reddish hue in this big storm (and elsewhere around the planet).
It’s the altitude of those clouds. Jupiter’s uppermost cloud layer is largely ammonia,
and the storm that makes up the Great Red Spot is incredibly tall meaning those upper
layers of clouds get hit with a lot of sun light. An interesting question now is what combinations
of elements are responsible for the other colours in Jupiter’s clouds; the planet
is generally a mixed palette of oranges, browns and reds. But other trace gases in Jupiter’s
atmosphere like ammonium hydrosulfide turned green when exposed to UV light in a lab. Don’t you guys think the chemistry going
on in Jupiter’s clouds is just awesome? Let us know in the comments below or you can
catch me on Twitter as @astVintageSpace. And don’t forget to subscribe for more DNews
every day of the week.

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