Jupiter Sports a Third Red Spot

Jupiter and I have something in common: we both suffer from acne.

Earlier this month astronomers working with the Hubble Space Telescope provided the best images yet of a third red spot on our solar system's largest planet. The blotch lies in the same cloud belt as the Great Red Spot (GRS) and to the northwest of Red Spot Jr. In images it appears about half Junior's size.

Red Spots
HST image of the three red spots. The Great Red Spot sits at right, Oval BA ("Red Spot Junior") is the lowest, and 2008 Oval 2 ("Spottie") is at left. The white ovals are also vortices.
M. Wong and I. de Pater (UC Berkeley)
"Although much smaller in extent, the [spot's] color is striking," says team member Michael Wong (UC Berkeley) in a press release. He also notes that the third spot resembles the other two red storm systems in infrared and ultraviolet light.

The astronomers used Hubble and Hawaii's Keck Observatory to capture "Spottie" (Junior's loathe to become Red Spot II) on May 9–11. Observations followed a color change in the oval noticed by amateur astronomers in March.

Among the astronomers on the research team is Christopher Go, an amateur from Cebu, the Philippines. Go joined the group in 2006 after being the first to announce that white spot Oval BA had turned red. (Oval BA remains Junior's official name.)

It's hard to remember that, being storms, the spots can come and go. Red Spot Jr. made quite a stir in 2006 when it shattered the GRS's treasured uniqueness. Oval BA coalesced in March 2000 from three, smaller white ovals that formed in the 1930s. It sparked little interest because its color stayed constant — just one more white dot in Jupiter's atmosphere.

That changed in February 2006 when Go reported the color transformation. Researchers still don't know why BA blushed, or even why the storms are red to begin with. The most popular theory is that the storms' ascending currents drag up chemicals from the lower atmosphere that turn red when exposed to sunlight. Spectroscopic observations of the spots, however, haven't confirmed the presence of the chemicals astronomers expected to find.

Spottie's not just another blemish on Jupiter's lovely face, though. Its appearance may signal larger changes for the gas giant. Philip S. Marcus, who teaches fluid dynamics at Berkeley, predicted in the April 2004 Nature a global climate cycle on Jupiter spanning roughly 70 years. He pinpointed the current cycle's beginning to the 1930s, the same decade the three white ovals that formed Junior appeared. In the cycle, established vortices (like Junior) merge or decay, reducing their number. This reduction also lowers the amount of turbulence in the planet's jet streams. Without the mixing caused by this chaos, the atmosphere cannot maintain a roughly uniform temperature.

"The average temperature on Jupiter will change by as much as 10 degrees Celsius," said Marcus in 2004, "getting warmer near the equator and cooler at the poles. This global shift in temperature will cause the jet streams to become unstable and thereby spawn new vortices." He argued that large changes would start in Jupiter's southern hemisphere in 2006 — just where all three spots appeared.

Never fear, our favorite Jovian feature since the 1600s will not disappear. Marcus says the GRS will endure because it lies too near the equator for a counter-vortex to form and destroy it. Spottie is another story, though.

"If this spot and the Great Red Spot continue on their courses," says Wong, "they will encounter each other in August, and the small oval will either be absorbed or repelled from the Great Red Spot."

The planet's flare-up will last a while yet. After all, poor Jupiter only has nature for a mother, not a dermatologist.

4 thoughts on “Jupiter Sports a Third Red Spot

  1. Nathaniel Sailor

    First it’s the GREAT RED SPOT, then it’s junior, now we have junior2(the smallest spot spotted on 2006). Will we have more red spots?

  2. Nathaniel Sailor

    First it’s the GREAT RED SPOT, then it’s junior, now we have junior2(the smallest spot spotted on 2006). Will we have more red spots?

  3. Frank

    Hi Ms. Camille,

    Fascinating article. I have a question for you regarding the longevity of the GRS. As a meteorologist I’m amazed at the GRS’s ability to maintain itself based on the fact that it is an atmospheric disturbance. On earth, our disturbances are ultimately driven by differential heating which create horizontal and vertical motions within the atmosphere with the ultimate goal being to relieve the stress being created by that differential heating. All this takes place on the scale of hours and (at most) days. My question is this: What is causing the GRS and why has it persisted for such an incredible length of time? What stresses within the atmosphere of Jupiter are causing it and why can’t they be alleviated?

    All the best,
    Frank

  4. Camille M. Carlisle

    Short answer: instability in the jet stream and no other spots around to squash the GRS out.

    Longer answer: Marcus speaks on this point somewhat in his 2004 Nature letter (linked in the news blog, fifth paragraph from bottom). What I’ve gleaned from that paper is that Jupiter’s strong Coriolis force (the force arising from the planet’s rotation, which affects cloud motions) affects the atmospheric currents. The GRS happens to be in a spot near the equator where, Marcus writes, the “Coriolis forces make the atmospheric flow nearly two-dimensional, an environment where vortices thrive. (Three-dimensional flow destroys vortices.)” As I say in the news blog, no cyclone exists counter to the GRS in the right place to merge with/destroy the GRS; Marcus (in the same Nature letter) concludes this absence results from a more three dimensional quality in the flow and a weaker Coriolis force. Without another vortex to destroy it, the GRS continues.

    I hope that helps. I recommend reading the Marcus paper: he goes into quite a bit of detail regarding the various troughs and zonal jet streams and might provide a more complete answer to your question. cmc

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