Event Jupiter 1st August

[ricci]

In the night of 1st August will happen a rare event of Jupiter's satellites : double transit and double shades of Io and Europa. Then only of this year!

www.pierpaoloricci.it/eventi/giovedoppi_eng.htm

[youreyes]

what does double transit and double shades mean exactly?

[Tiassa]

what does double transit and double shades mean exactly?

"Double shades", I think, refers to "double shadows", or, two shadows, as the "double transit"—i.e., transits of two bodies—occurs across the face of Jupiter.

Strangely, Pierpaolo Ricci's website, the reference link in the topic post, is the only mention I've found of a double transit of Jupiter on Aug. 1. Google is littered with discussion of the January double transit of Europa and Ganymede.

Of course, the reference page lists seventeen double transits of Galilean satellites in 2012, so the sentence, "Then only of this year!" makes absolutely no sense to me.

Amateur astronomers with sufficient telescopes can certainly try to witness the event; the rest of us will do as we always do, wait for the pictures to emerge the next day.

Indeed, that seems an easier view of the event than trying to figure out who else thinks it's happening.

Of course, since celestial events are only visible from part of the world, there might be a reason we in North America aren't hearing much about it.

[youreyes]

So double shades = double shadows = double transit = transit of two bodies at same time across face of Jupiter when viewed from Earth perspective? Do those two objects align in one line or are they just covering the view of Jupiter?

[Tiassa]

They'll be tiny dark dots against the background of Jupiter. A simulated view, from another occasion:

Approximately, maybe: A simulated view of an unknown double transit, generated by Celestia; via Wikipedia