Today, at 2:45 p.m. PDT (5:45 p.m. EDT or 10:45 p.m. GMT), be sure to tune into the extra special Venus transit live video feed from the famous Mt. Wilson Observatory. I will be there, co-hosting a pretty awesome live event from the historic site with Mike Simmons, President and Founder of Astronomers Without Borders. We also have a surprise, rather sci-fi announcement in store too. For a run-down of all the festivities and the live feed, take a look at the AWB transit pages.
I will be surrounded by real astronomers with huge telescopes, so there will likely be lots of opportunities to see me geek out over some awesome views of this once-in-a-lifetime event (well, two if you saw the 2004 transit… or if you’re really young and live to see the 2117 Venus transit!). I will also be taking my patented “eclipse viewing” kit — a $1 pair of eclipse glasses and my Nikon CoolPix camera — to see if I can get a very amateur photo of Venus’ silhouette!
Of all the amazing things I plan to look at through my future telescope (yes, I’m still saving), this event didn’t even cross my mind. Not surprising really, it’s probably never been observed before: Io’s whole shadow transiting across the large Jovian moon, Ganymede.
But on August 16th, that changed when Christopher Go from Cebu, Philippines used his 11-inch Celestron telescope to capture the sequence of events as Io passed in front of the Sun, casting a near-perfect shadow on the large moon of Ganymede. If you were standing on Ganymede’s surface, looking at the Sun, you would have seen an Io solar eclipse.
My favourite thing about this animation is that both moons are very detailed, even at this resolution. You can see mottled shades on Ganymede, and I think the spin of Io may even have been captured.
A wonderful testament to Christopher Go’s astronomy skills and a fantastic example of how advanced our amateur astronomical equipment is becoming…
UPDATE: It turns out that little Io is getting its own back for last July’s eclipse by Ganymede, plunging the smaller moon into darkness. In the following video by OccultDave on YouTube, over a period of about 16 minutes, Io (the dot to the far-right) dims dramatically as Ganymede (the dot in the middle, next to the bright disk of Jupiter) blocks the sunlight: