There's a little black spot on the sun today

Today, November 8, the planet Mercury passes inferior conjunction with the Sun, where it is in between the Sun and Earth. Because of the tilt of the planetary orbit, Mercury is usually not QUITE aligned, but passes either above or below the solar disk. This time, however, the planet passes right across the Sun for a "transit." Transit seasons are early November and May. November events are separated by intervals of 7 or 14 years. May transits (which take place with the planet farther from the Sun) are rarer, and can, but don't have to, recur in 14 years. (Transits of Venus are far rarer. There were none in the twentieth century; the last one was in 2004, the next in 2012.)

Unfortunately, Transits of Mercury are NOT visible to the naked eye, even with appropriate
filters, but are readily visible with the telescope. However, they should be viewed by projection only; do not even try without professional-level knowledge or help. The event begins at 1:12 PM

CST (2:12 EST, 12:12 MST, 11:12 AM PST, 9:12 AM Hawaii), and lasts for about 5 hours as the planet slowly moves in orbit. Only the western US and Canada will witness the whole thing before sunset. The timings of such transits were once used in attempts to local times and thus longitudes. This description courtesy of Jim Kaler: http://www.astro.uiuc.edu/~kaler/skylights.html

Since this is a telescopic event, and then only through solar safe telescopes, I thought I'd provide our OTAstronuts with a virtual viewing of the transit. I'll be here at JPL, with three solar-safe telescopes, Mojo is at work with one additional safe telescope, and our frequent sidewalk astronomy telescope operators Gary and his daughter Elizabeth are setting up a solar safe telescope at Elizabeth's school today.

So sit back, and use these links. The transit begins at 11:10 a.m. here on the west coast and ends at 4:10 p.m. If you miss this one, don't worry, it'll happen again in 2016!

A webcast - one of many, you can probably find others if this is busy using your favorite search engine: http://www.exploratorium.edu/transit/

A nice visual description, shows size of Mercury - looks fine on the screen, white text doesn't show up on printed copies: http://www.exploratorium.edu/transit/what.html

Todays sunspots here - the sunspot image also shows size of Earth and Jupiter for a great size explanation. :-) http://sohowww.nascom.nasa.gov/

Finally, this transit is not visible everywhere on Earth. The transit will be widely visible from the Americas, the Pacific Ocean, eastern Asia, and Australia

Jane Houston Jones
Senior Outreach Specialist, Cassini Program
JPL - 4800 Oak Grove Drive, MS 230-205
Pasadena, CA 91109 818-393-6435
jane.h.jones@jpl.nasa.gov
Cassini Saturn Observation Campaign
http://soc.jpl.nasa.gov/index.cfm