Jupiter's Great Red Spot

These panels show closeups of Jupiter, centering near the Great Red Spot (GRS), as a function of time. The upper left image, false-colored blue, is a detail of a Hubble Space Telescope image obtained in an observing program headed by Reta Beebe (New Mexico State University). The remainder of the images were taken at the NASA Infrared Telescope Facility with the NSFCAM near-infrared facility camera/spectrometer near 4.8 microns wavelength, where they show thermal emission emanating from cloudtops in the atmosphere. They have been falsely colored red to denote thermal emission rather than reflected sunlight. These NASA IRTF observations were acquired and reduced by John Spencer of Lowell Observatory; Glenn Orton, Kevin Baines, James Friedson, Padma Yanamandra-Fisher of the Jet Propulsion Laboratory, California Institute of Technology; Joseph Spitale of the California Institute of Technology; and Keng Lim and Ford Wong of Imperial College, London. The Great Red Spot is one of the principal targets planned for intensive investigation by the Galileo Orbiter mission.

Note that in February, only the thin southern ``lip'' (arrow) of the GRS periphery is observable, with a little more in March (arrow). By April a narrow, but bright (clear) line has appeared and covered the northern periphery. By May, the northern clear region has structure and the southern lip is wider. By July, another thin, broken bright region has appeared around the inner periphery of the GRS. Between then and August, this bright periphery has grown wider - although it is not in a constant position. Numerous dark vortices with bright peripheries are apparent, passing the from west to east, relative to the GRS.

Similar observations of the Great Red Spot will continue and will focus on the behavior during the time period of early July, 1996, when Galileo's first orbital encounter takes place - for which the GRS is the primary target for synoptic measurement by all the remote sensing instruments. Observations such as these during that time period will help in the interpretation by providing a broader area of coverage than that which will be covered by the spacecraft observations.

This image is available in gif format via anonymous ftp to lono.jpl.nasa.gov ( in pub/irtf as grs5ch95a.gif. It is catalogued as JPL color negative P-46229 BC.