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Jupiter transits tonight and sunday


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Stellarium is showing me that io and its shadow transits Jupiter's disk tonight from around 11pm and then tomorrow eve (29th) we get two for the price of one with europa and ganymede crossing the disk whilst the GRS follows close behind. A great opportunity for all you imagers!

 

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Just packed up and come in from a lovely session as the dew was getting a bit too much to deal with. Started with Saturn but moved to Jupiter just before the Io transit. Had some really good views of it most of the way through, although about a quarter in, some high cloud dimmed it considerably before clearing to leave some very good seeing at times. The 8.5 showed quite a lot of belt detail and at the mid point the shadow looked just like someone had drilled a hole through Jupiter to reveal the black of space beyond! 

Finished with a quick look at the moon and a browse along the terminator. Great to get a decent session in after the recent run of weather here. Hoping tomorrow can deliver too. 🙂 

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I had a great view from Essex using my 10” Dob at 150x. It was fascinating to watch Io creeping ever closer to Jupiter’s limb, then becoming a bright dot on the disk. I followed it for over 10 minutes until it became lost in the glare of its parent planet. I then watched as the shadow started as a notch in the limb and became an inky black dot.

It was Danish astronomer Ole Roemer who in 1676 became the first person to measure the speed of light by accurately timing these events. I can only marvel at his intellect, no computer to crunch the numbers.

Something for us all, observer imager or armchair astronomer.

Ed.

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Ahhh it was Io. I just commented on another post mentioning I’d seen a moon transitioning across Jupiter but didn’t check which one. 
 

I managed to get upto 266x with a 10" dob. I need some more eyepieces really as the sweet spot would’ve been a little less. It looked better at lower magnification but was good enough at 266 I felt it was worth it. I had a go at Saturn at 266 but it was too low and too close to a street light and looked terrible. 

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21 hours ago, ShrewView said:

Just packed up and come in from a lovely session as the dew was getting a bit too much to deal with. Started with Saturn but moved to Jupiter just before the Io transit. Had some really good views of it most of the way through, although about a quarter in, some high cloud dimmed it considerably before clearing to leave some very good seeing at times. The 8.5 showed quite a lot of belt detail and at the mid point the shadow looked just like someone had drilled a hole through Jupiter to reveal the black of space beyond! 

Finished with a quick look at the moon and a browse along the terminator. Great to get a decent session in after the recent run of weather here. Hoping tomorrow can deliver too. 🙂 

May I ask what telescope were you using?

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On 29/08/2021 at 07:52, NGC 1502 said:

.It was Danish astronomer Ole Roemer who in 1676 became the first person to measure the speed of light by accurately timing these events. I can only marvel at his intellect, no computer to crunch the numbers.

Something for us all, observer imager or armchair astronomer.

Ed.

I assume it was part of the general investigations going on at the time to resolve the 'longitude problem', which requires a consistent way of measuring time when at sea.

Various methods were attempted, including attempts to tabulate the movement of the Moon, and one was to use the movements of the Galilean moons to act as a celestial clock.

If this was tabulated and compared to observations, the discrepancy as the planet moved further from the Earth would have become apparent.

In reading about the history of this (very well covered in Dava Sobel's book Longitude), there is often reference made to the 'Lunar Method', but not so much to using Jupiter's moons as a timepiece, though the Wikipedia article on the history of longitude mentions both the Jovian satellites and magnetic declination as alternatives that were investigated.

 

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10 hours ago, Grumpy Martian said:

May I ask what telescope were you using?

It was my old 8.5inch newtonian. Had it since about 1985 and still gives me some great views on a good night. 

Can't get through the clouds we had last night though 😠

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1 hour ago, Gfamily said:

I assume it was part of the general investigations going on at the time to resolve the 'longitude problem', which requires a consistent way of measuring time when at sea.

Various methods were attempted, including attempts to tabulate the movement of the Moon, and one was to use the movements of the Galilean moons to act as a celestial clock.

If this was tabulated and compared to observations, the discrepancy as the planet moved further from the Earth would have become apparent.

In reading about the history of this (very well covered in Dava Sobel's book Longitude), there is often reference made to the 'Lunar Method', but not so much to using Jupiter's moons as a timepiece, though the Wikipedia article on the history of longitude mentions both the Jovian satellites and magnetic declination as alternatives that were investigated.

 


Thanks for that, didn’t realise that the accurate timing of Jupiter’s moon events was part of solving the Longitude problem. Somewhere in my book collection I have Dava Sobel’s book, I must dig that out sometime and reacquaint myself with the fascinating history.

Ed.

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