Hubble's Universe Unfiltered

  • January 5, 2009

    Episode 4: Jupiter Gets the Measles

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    The most prominent feature on the planet Jupiter is a large, ruddy oval that is simply called the Great Red Spot (GRS). The GRS is a giant storm in Jupiter's atmosphere that has been remarkably stable. In fact, it may have been observed as early as the 1660s. During the intervening centuries, the GRS was not just the largest but also the only red spot ever seen on Jupiter. That situation changed when a formerly white storm turned brown in late 2005, and then red in early 2006. And yet another red spot appeared in spring 2008. After such consistency for hundreds of years, Jupiter appears to be breaking out in red spots. Join us for a look at this historic case of planetary measles.

    • Drawing of Jupiter, 1677

      A great drawing of Jupiter (right) with something that looks an awful lot like the Great Red Spot was published by Giovanni Cassini in the "Journal des Scavans" (the earliest scientific journal published) in 1677. This spot was observed until the early 1700s. However, the observational record is continuous from the present day back to only about 1830. We do not know whether the spot observed by Cassini is the same spot that we call the Great Red Spot today.

    • Some Hubble color images of Jupiter show a blue tint on one side of the planet and a red tint on the other side. See, for example, this image from 1994: The Giant Planet Jupiter.

      The reason for the tints is that Jupiter rotates very quickly, in about ten hours. Hubble does not take color photos but rather creates color from separate red, green, and blue exposures. Between the time that the red exposure was taken and the blue exposure was taken, the planet rotated a small amount. When the exposures were aligned and combined, a small part of Jupiter only appears in the red exposure (the red tint) and a small part only appears in the blue exposure (the blue tint). This combination of exposures also makes Jupiter appear more oval-shaped than it really is.

    • The spot that we call "Red Jr." formed in the year 2000, but it did not turn red until early 2006. Astronomers know it by the simpler name, "Oval BA." It arose from the merger of Ovals FA, DE, and BC during 1998-2000. In late 2005, Oval BA was observed to turn brown, and by February of 2006, it was the same reddish color as the Great Red Spot. That is when folks started calling it Red Jr. Incidentally, some astronomers don't like the nickname of Red Jr., and one referred to it in a NASA press release as the "not-so-Great Red Spot."

    • The "Baby Red Spot," as we call it, is a nickname for the South Tropical Little Red Spot. Subsequent observations to the ones shown in the video podcast show that the storm was disrupted by its encounter with the Great Red Spot and did not re-form. Some "probable" remnants remained together for several weeks, but at a much smaller size than when the storm was red. This smallest of red spots only lasted for about 3 months, and raises the intriguing possibility that there could be more to come.

    Image notes

    Hurricane Isabel (2003) over the Atlantic Ocean
    Credit: Jeff Schmaltz, MODIS Rapid Response Team, NASA/GSFC

    Eye of Hurricane Isabel (2003) from the International Space Station
    Credit: NASA

    Hurricane Isabel (2003) off the Outer Banks
    Credit: Jacques Descloitres, MODIS Rapid Response Team, NASA/GSFC

    Hurricane Isabel (2003) from the International Space Station
    Credit: NASA

    Jupiter's Great Red Spot from Voyager 2
    Credit: NASA/JPL-Caltech

    Earth, Western Hemisphere
    Credit: NASA, GSFC, et al. (follow link for complete credits)

    Jupiter from Hubble
    Credit: Reta Beebe, Amy Simon (New Mexico State Univ.), and NASA

    Great Red Spot Montage
    Credit: The Hubble Heritage Team (STScI/AURA/NASA) and Amy Simon (Cornell U.)

    Great Red Spot and Red Jr. - April 25, 2006
    Credit: NASA, ESA, I. de Pater, and M. Wong (UC Berkeley)

    Jupiter Timelapse Sequence from Cassini
    Credit: NASA/JPL/University of Arizona

    Three Red Spots on Jupiter
    Credit: M. Wong and I. de Pater (UC Berkeley)

    Three Red Spots Sequence, May to July 2008
    Credit: NASA, ESA, A. Simon-Miller (GSFC), N. Chanover (NMSU), and G. Orton (JPL)

    Jupiter in Infrared with Great Red Spot and Red Jr.
    Credit: Gemini Observatory/AURA, Chris Go