Wednesday, September 02, 2009

Oh, Jovian Moons - Where Art Thou?

Tonight, Jupiter's main four moons move either directly behind or directly in front of Jupiter from our perspective, leaving the visual image of the gas giant unusually alone. Ganymede and Europa move in front of the planet, whereas Io and Callisto will move behind it, all at around the same time. It's rather rare for such an event to occur, about 12 or so times per century!

Anyway, I used my Orion 6" Dob to check it out, starting at about 10PM or so tonight. No real photos, but I can show you how it appeared through my scope using captured real-time apparent views from Calsky. Seeing conditions were actually pretty good, about 4/5.

10:25PM US CST (03:25 UTC)

Ganymede - Europa - Jupiter - Io

11:05PM US CST (04:05 UTC)

Ganymede - Jupiter

11:38 US CST (04:38 UTC)

Ganymede - Jupiter

(Bye Ganymede!!!!)

00:07 US CST (05:07 UTC)

Just Jupiter!

This was quite a neat sight, albeit rather odd. To see Jupiter alone with a dark, lonely background and no moons surrounding it took some getting used to! I studied it for about 35 minutes, watching Europa's and Ganymede's shadows slowly make their way across the gas giant's disc. I fancied that I could still see the scar left behind by the comet/asteroid when impacting it several weeks ago. Not 100% sure about that, though.

Anyway, a great event to observe and I am glad I stayed up for it. Luckily I have no meetings at work tomorrow so can get away with some head-down time ;-)


Jared said...

I was out at the dam watching Jupiter. Didn't know about the transits but I wasn't out there that late either.

When I first saw it only Ganymede and Io were visible...I thought I was going crazy and looking at Saturn with the edge on rings. A quick reality check took care of that :)

Ewan Bryce said...

Hi Phil! It sounds like you had a great time with this observation. I was planning to take in a view, but the clouds put a stop to that. As it was I would've only been able to follow Jupiter up until 02:30 BST so I would have missed the main event anyway. I'm glad you got to witness this once in a decade occurrence.

Clear skies,


Phil said...

Thanks, Ewan! I was going to stay up later and watch the moons re-emerge but was too tired. A nice stroke of luck for us to have clear skies last night, we have had absolutely rubbish weather for astronomy this year.

Clear skies!

Phil said...

Jared - makes me wonder how often folks watch stuff up there and have no clue that a specific event is occurring, then scramble to get online and check... I haven't been to the dam in ages (weeks!). Soon, hopefully!

Roopesh said...

Hi Phil..!

Nice observation.. I do not have any scope as of now... but planning to buy very soon...