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Old 10-05-2018, 12:13 AM
Tropo-Bob (Bob)
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Join Date: Sep 2013
Location: Cairns
Posts: 1,584
Europa Transit Observation (at Opposition)

I viewed this my Vixen ED 115mm this evening (May 9th), using 127x & 178x.

Jupiter looked striking and the red spot looks to be a deeper red than I have seen it for some decades.

When the transit began, I could pick out Europa as a bright point of light, but failed to see the shadow. However, some minutes later, I did faintly see the shadow nearby, but Europa quickly disappeared.

Europa's shadow become darker and more distinct. However, I did not see Europa again till near the end of the event.

It all happened in the last few minutes. With 15 minutes to go, the shadow was obvious, but Europa could not be seen. I viewed it again some 10 minutes before Europa's egress. Both could now be seen very close together, but without any overlap. From this point, the shadow began to disappear, whereas Europa shone more brightly, as it drew closer to Jupiter's not-so-well-lit limb.

Prior to the event, I thought the transit was occurring during the exact time of opposition. I reasoned this because Europa's shadow was due to appear first, then leave last. However, Jupiter is round and in reality, the shadow traversed across the planet closer to its equator, thus, had a longer path to travel.
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