Saturn's North and South aurora observed by Cassini camera in visible wavelengths.
+ UVIS simultaneous observationsUlyana A. Dyudina, Danika F. Wellington, Shawn P. Ewald,
Andrew P. Ingersoll.+ Wayne Prior et al.
Aurora Australis
SpectrumMeasuredby Cassini
Lab simulation
(Aguilar et al. ApJ. 177, 2008)
Rayleigh/nm
Saturn periodicities
Saturn day 0
Day 2
Day 5
Day 7
Saturn periodicities
Saturn day 0
Day 2
Day 5
Day 7
Voyager SKR period: 10.6564±0.002 h
Our Aurora period = Voyager’s= = 10.65±0.06 h
SKR rotation period
Gurtett, et al. GRL 37, L24101, 2010
10.65±0.06 h
Nov. 2010 aurora
Nov. 2010 aurora
Nov. 2010 aurora
Nov. 2010 aurora
Nov. 2010 aurora
...+ UVIS simultaneous observations
…+ Wayne Prior et al.
Rev 119 UVIS data (2009 day 280) painted on Saturn:
UVIS 2009 day 280 data for ISS snakes
281T00:07
ISS “snakes” 280T23:00
UVIS FUV 60 mrad long low-res (1.5 mrad wide) slit is aligned E-W, spatial sectors 27-32 (out of 0-59) overlap ISS NAC and the “Snake” features
As time progresses (upwards in UVIS image) bursty quasi-periodic features rotate across Saturn’s nightside
Night Side UVIS counts time-series: bright bursts are deep, show up more at long wavelengths (short wavelengths are absorbed by methane)
Figure from Gustin et al. 2008• Large methane
columns above snakes, other nightside spots imply electron penetration hundreds of km below usual ~1100 km auroras found by Gerard et al. 2009
• Visually, “curtains” at limb are higher than “snakes”
• Tests methane distribution models
snake
✚
ConclusionsAurora is ~1200 km tall
Aurora is few hundred km above Saturn’s “surface”, bright events are deeper
Aurora may form double curtain
Aurora is red
Auroral rotation matches SKR rotation period
I would love your suggestions on planning auroral observations with ISS
