Saturnian Moon Transits

Saturn is quickly moving to the west by 10pm this month, and so tomorrow
night up at the Peak, I¹m going to spend possibly my last time observing it
this season provided the seeing is good. Looking at Saturn closely with my
Mac¹s Starry Night Pro 6 planetarium, I see that Tethys will be transiting
Saturn¹s disc between 8-10pm with a tiny shadow following by one hour (a
shadow transit). This shadow will be way too small to notice with my modest
10 in. Mak ­ but this observation brings up a good point: as Saturn appears
more edge-on to us on the Earth during the next couple of years, we will get
to see more of its larger moons transiting across its disc ­ this hasn¹t
happened since the last edge-on apparition back in 1995. This will go on for
the next few years ­ both sides of Saturn¹s next edge-on apparitions during
2009/2010. I can¹t wait to see Saturn without its rings ­ naked. By then,
it will be possible to see four of Saturn¹s largest moons Titan, Dione,
Rhea, and Tethys all in line with Saturn¹s equator transiting over and
throwing their shadows on Saturn¹s disc ­ something I haven¹t seen before.
Saturn¹s fainter moons (Enceladus and Mimas) will also be seen more easily
without the usual large bright rings visible. I¹m not sure how many times
during 2009/2010 the Earth will be aligned edge-on with Saturn¹s rings, but
it happened three times during 1995.

Peter Natscher
Monterey

-- 
Party time! GSSP is over 250 attendees: http://www.goldenstatestarparty.blogspot.com
TAC Stats Tracking - on the observers.org menu.
Mailing list preferences: http://seds.org/mailman/listinfo/sf-bay-tac