On the morning of 12th August we took advantage of the clear skies to observe the eclipse of Europa caused by the shadow of Ganymede and the transit of Io across the disk of Jupiter.

The evening began at 10pm setting up and aligning a Meade 8” SCT LX200 which I was using whilst my telescope mount is being fixed; we also had a Celestron 11” SCT up and running.

I started off with a good old deep sky object, M57 which the goto found and almost centred the object. I then selected some other objects near by which included M27, M71, M11. We could not see Juniper during the early part of the evening, as the trees were too high. After a quick cup of coffee I moved the telescope down to M16 (Eagle Nebula) of which you could only see the stars and no nebula, as this is too faint even for Peter’s eyes. M10 and M12 in Ophiuchus were low in the sky and the stars could not be resolved as there was too much murk low down but could be seen as fuzzy patches, also by this time the moon had risen and made deep sky observing difficult.

Despite the moon, I flicked through my Stars and Planets book where I noticed a Galaxy, NGC 6946 which showed as being within the Cygnus border. I could not see this face on galaxy in the 8”, maybe it was the moon stopping me from seeing the galaxy so we tried to see the Galaxy in the Celestron 11” but still nothing. Using the computer program The Sky 6 we confirmed the telescope was looking in the right area of the sky. Interestingly enough the Celestron handset reported the Galaxy as being in Cepheus and not Cygnus and determined to see the Galaxy the CCD came out and a series of shots were taken and there was the Galaxy for all to see.

NGC6946, image by Ian Hargraves

During this time we witnessed a number Perseid meteors, I would say about 10 -15.  The meteors seen were mainly going through Cygnus and a couple witnessed going through Pegasus.  One sporadic Meteor was seen going through Scutum. By now it was about 1am BST and we took time out to watch for any more meteors and more importantly waiting for Jupiter to come out from behind the bushes and that annoying sticking out branch.

 Around 1:30am the telescopes were turned to Jupiter ready to witness the Eclipse of Europa and the Transit. The Picture below shows the position of the moons when we first started viewing the event.

  At 1:45 Io appeared to be on the limb of Jupiter and at this point Io was still appearing as a pin point of light but was not twinkling like Ganymede and Europa were.

Constantly watching the movement of the moons over the next 15 minutes Io disappeared into the body of Jupiter and the shadow of Io appeared on the disc of Jupiter and could be easily seen as the atmospherics were good.

Between 2am and 2:45am was just a waiting game whilst we wait for the Eclipse to occur.

At 2:15am we could see the two moons just about and used the shadow of Io to ensure the telescope was focused as best as possible.  The image below gives you a reasonable illustration.

As 2:45 was approaching it was quite obvious Europa was turning a darker brown as Ganymede’s Shadow fell across the disc of Europa.  Within minutes of witnessing the darkening of Europa we could see Ganymede carried on moving and Europa totally disappeared and it was quite obvious Ganymede did not pass in front of Europa but below Europa which is why Europa disappeared due to Ganymede’s shadow.

Between 3am and 3:30am not too much was happening as we packed away the 8” and took passing glimpses in the 11” to make sure we weren’t missing much.  I think I can safely say the eclipse was over at 3:30am as the two moons were visible once again but we could not split the two moons as they were still too close.

I think everyone who witnessed this event would agree it was well worth the 4 hours sleep before work the next morning.