Jupiter Io Eclipse

[David Levi]

I was out last night in the Brecon Beacons with my 12" dob. One of my aims for the night was to witness the moon Io (It was Europa - thanks @AstroTim) emerging from it's eclipse by Jupiter.

I had experienced this before but did not know about this phenomenon at the time and missed the moment of the moon revealing itself.  I only noticed that, one minute the moon wasn't there and then after being away from the eyepiece for a few minutes it was quite a way from the disk of Jupiter.

Before going out I had checked the website Javascript Jupiter to see what events were taking place on and around the planet and saw that Europa would be emerging from eclipse at 10.20pm.  I made sure that I was glued to the eyepiece at the appropriate time. I didn't know what to expect - maybe a quick reveal like a magic trick!

It was like waiting for the proverbial kettle to boil. Then it dawned on me that I could see a faint speck of light, which was better with averted vision, about a Jupiter radius away from the planet. The speck grew brighter gradually over the period of a minute or two until Europa was fully revealed. I wasn't paying attention to the time as I was engrossed in the event but it was something like that time period.

Edited September 14, 2020 by David Levi

[John]

Nice report of this event

By the time Io emerged from the shadow Jupiter had gone behind a tree for me so It's good to read your report of the re-appearance

[AstroTim]

Interesting event, although just been checking on SkySafari and wasn’t it Europa that was being eclipsed at that time? I was actually observing Callisto transiting Jupiter at around the same time, but didn’t realise that Europa was also being eclipsed, and would soon emerge, so missed it completely. I will have to look out for it another time. I only knew about Callisto because I could see a dark dot on Jupiter and (after checking for debris on the eyepiece) went inside to look up what it could be (which probably coincided with when Europa emerged).

 

Tim

[David Levi]

30 minutes ago, AstroTim said:

Interesting event, although just been checking on SkySafari and wasn’t it Europa that was being eclipsed at that time?

Yes Tim you are correct. My laziness in not checking!

[AdeKing]

27 minutes ago, AstroTim said:

Interesting event, although just been checking on SkySafari and wasn’t it Europa that was being eclipsed at that time? I was actually observing Callisto transiting Jupiter at around the same time, but didn’t realise that Europa was also being eclipsed, and would soon emerge, so missed it completely. I will have to look out for it another time. I only knew about Callisto because I could see a dark dot on Jupiter and (after checking for debris on the eyepiece) went inside to look up what it could be (which probably coincided with when Europa emerged).

Tim

Snap, I also missed the reappearance of Europa as I was engrossed in the Callisto transit. I normally lose the moon's once they start to cross the disc, but was staggered by how dark Callisto was.

Only when returned from double checking what I was seeing did I notice that another moon had appeared.

Thanks for your account of its reappearance.

[David Levi]

I couldn't see the shadow of Callisto. The seeing was awful where I was. The humidity must have been in the high nineties. At the end of the session it was like someone had chucked a bucket of water over the telescope. It was dripping wet.

[AdeKing]

8 hours ago, David Levi said:

I couldn't see the shadow of Callisto. The seeing was awful where I was. The humidity must have been in the high nineties. At the end of the session it was like someone had chucked a bucket of water over the telescope. It was dripping wet.

I've just checked up on the Sky & Telescope Jupiter's Moons site and I think it was actually Callisto itself.

They list the Callisto shadow transit as starting at about 07:30 this morning.

This is why I was so shocked as Callisto was so dark against the disc that it did look like a shadow transit. A first for me and something new learned.