The Great Red Spot Plunge

Here is NASA’s description of this video: This animation takes the viewer on a simulated flight into, and then out of, Jupiter’s upper atmosphere at the location of the Great Red Spot. It was created by combining an image from the JunoCam imager on NASA’s Juno spacecraft with a computer-generated animation. The perspective begins about 2,000 miles (3,000 kilometers) above the cloud tops of the planet’s southern hemisphere. The bar at far left indicates altitude during the quick descent; a second gauge next to that depicts the dramatic increase in temperature that occurs as the perspective dives deeper down. The clouds turn crimson as the perspective passes through the Great Red Spot. Finally, the view ascends out of the spot.

Video Credit: NASA

Another Look at the Giant Red Spot

This Jovian image was processed from data taken by the JunoCam instrument aboard the Juno spacecraft by amateur scientists Gerald Eichstädt and Seán Doran. North is to the left of the image. The spacecraft was a bit more than 16,500 km from the tops of the Jupiter’s clouds when the image was taken at 23:12 UTC on 10 July, 2017, during its seventh close flyby.

Image Credits: NASA / JPL-Caltech / SwRI / MSSS / Gerald Eichstädt / Seán Doran

Why is the Giant Red Spot Red?

jupiterganymede_hstThe color of Jupiter’s Great Red Spot is probably the result of simple chemicals being broken apart by sunlight in the planet’s upper atmosphere. At least that’s what’s suggested by analysis of data from lab experiments and from NASA’s Cassini mission. (“Hold it,” I hear you cry. “Cassini is a Saturn mission.” Yes, it is, but it did a Jupiter flyby on the way.) Those results contradict the other leading theory for the origin of the spot’s striking color—that the reddish chemicals are stirred up from beneath Jupiter’s clouds.

Jupiter possesses three main cloud layers which occupy specific altitudes in its skies; from highest to lowest they are ammonia, ammonium hydrosulfide and water clouds. In lab experiments researchers zapped ammonia and acetylene gases, known to be present in that upper layer, with ultraviolet light, simulating the Sun’s effects on those materials. This produced a reddish material, which the team compared to the Great Red Spot as observed by Cassini’s Visible and Infrared Mapping Spectrometer (VIMS). They found that the light-scattering properties of their red concoction nicely matched a model of the Great Red Spot in which the red-colored material is confined to the uppermost reaches of the giant cyclone-like feature. If red material were being transported from below, it should be present at other altitudes as well, which would make the red spot redder still.

When the same sort of test were performed on ammonium hydrosulfide which makes up a lower layer, the researchers found that, instead of a red color, the products their experiment produced were a shade of bright green.

The Great Red Spot is a long-lived feature in Jupiter’s atmosphere that is as wide as two earths.

Image Credi: NASA

The Not-So-Giant Red Spot

HubbleJGRS_900The most prominent feature on Jupiter is a storm called the Giant Red Spot. The most recent Hubble observations measure the spot to be about 16,500 km across. That’s the smallest ever measured by Hubble and big decrease from the 23,300 km measured by the Voyager 1 and Voyager 2 flybys in 1979. Telescopic observations during the 19th-century indicated a width of about 41,000 lm on its long axis. Current indications are that the rate of shrinking is increasing for the long-lived storm.

Image Credit: NASA