Jupiter's Red Spot--The Auroral Connection

Since it was discovered in 1665 Jupiter's Giant Red Spot has come and gone--for reasons not known. At times, it merely may have been that no one with adequate telescopes was paying attention. The Red Spot was weak or not observed at all during the rest of the 17th century.

However, this period was the time of the Maunder Minimum--an epoch when there were very few sunspots. For reasons such as this, the suggestion has been made that Jupiter's Red Spot, like the Earth's aurora, is strongly affected by solar activity.

When the 11-year solar cycle is at its peak, sunspots are most numerous and conspicuous. From these regions on the sun's surface copious quantities of particles, mostly protons and electrons, are cast out. The ever-present outward flowing solar wind is enhanced by these additional particles, the result on Earth is more auroras, magnetic disturbances and disruption to radio communications.

Jupiter, too, has its auroras, and likewise these undoubtedly are affected by the flow of particles reaching that planet from the sun. However, associated with the changes in particle emission from the sun are related changes in ultraviolet radiation. It is this ultraviolet light rather than the solar wind particles which causes changes in Jupiter's Red Spot, according to a recent suggestion by Dr. Kenneth Schatten of Boston University.

If the ultraviolet hypothesis is true, and Dr. Schatten is not entirely convinced that it is, 1979 and 1980, being years of sunspot maximum, will continue be good years for seeing Jupiter's Red Spot just as they will for seeing the Northern Lights.