Cassini Solstice Mission: Saturn Aurora Campaign

Saturn Aurora Campaign - Science Blog -- Luhmann

Space Weather at Saturn During the 2013 Auroral Campaign

March 22, 2013

This animation shows an example of a recent space weather event forecast derived from such observations by Goddard Space Flight Center space weather lab and illustrates the kind of information we will have to work with to understand what Saturn's aurora is responding to. Click on the image to view the animation. Credit: Goddard Space Flight Center

We know from previous Saturn auroral campaigns that conditions in space, in particular enhancements in conditions in the solar plasma wind that flows through the solar system, influence the brightness of the emissions there. This response resembles that of Earth's auroras although there are different details of the solar wind interaction that are quite different in the two planetary magnetospheres. Nevertheless we are hoping that solar activity helps trigger some brightenings that Hubble sees during the upcoming auroral campaign.

An interesting fact in Saturn's case is that because of the large distance of Saturn from the Sun compared to Earth, the solar wind now passing 1 AU [astronomical unit, or distance between the Sun and the Earth] will be affecting Saturn (at 10 AU) in mid-to-late April. It takes about 4 days for normal solar wind to reach 1 AU (Earth) but fast CME transient flows can arrive in about half that time. The solar wind speed is roughly constant all the way out to Saturn at ~10 AU. However the CME fast flows decelerate as they move out through the slower background wind, so the arrival time anywhere requires some modeling and is always somewhat uncertain.

In addition, if any faster traveling outbursts from Coronal Mass Ejections occur in the next weeks that are headed toward Earth, those may affect Saturn during the campaign.* Thus NOW is the time to be looking at space weather for the April Saturn auroral campaign.

Janet Luhmann
Space Science Laboratory, University of California, Berkeley
Cassini INMS (Ion and Neutral Mass Spectometer) Team Member
Principal Investigator for IMPACT, (plasma and fields instrument) on the STEREO mission studying the Sun

Notes: The animation shows an example of a recent space weather event forecast derived from such observations by Goddard Space Flight Center space weather lab and illustrates the kind of information we will have to work with to understand what Saturn's aurora is responding to. We will be watching the Sun closely for the next weeks and hoping for some action. For more information on Space Weather at Saturn visit: http://stereo.ssl.berkeley.edu/SAC2012/

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Jet Propulsion Laboratory