If Your Skies Are Clear Check This Out

[Refractordude]

Io's transit of Jupiter. Right click the image.

[JayTee]

Notice how close the shadow is to the disk of the moon.

I had an interesting encounter 4 years ago the night of Jupiter's opposition. I was observing Jupiter knowing that there was going to be an Io Transit. I could see Io entering Jupiter's disk from the telescope's right but I never saw it or its shadow as it traveled across the face of Jupiter. I didn't see it again until it exited on the opposite side of the planet. For a few days I sat and thought about why I couldn't see Io's shadow. Then it dawned on me, Jupiter was at opposition so the Earth was directly between Jupiter and the sun. Meaning that Io was also directly covering up its own shadow because of this yearly planetary alignment. Once I realized this, I thought what a cool effect that can only be seen once a year.

Notice that your stellarium simulation is very close to Jupiter's opposition date.

Cheers,
JT

[Refractordude]

Hello JayTee:

Thanks for that info. Unfortunate the clouds rolled in. I will have to wait until next time.