Shadows in the Daytime

1997 Oct 27

I just saw a shadow in the daytime. Why is this a big deal, you ask? Because the shadow was on Jupiter and the Sun was shining on me. (OK, actually I was in the shade of my house, you'll give me that much literary license, right?)

David North, Akkana Peck and I had been discussing whether it would be possible to see a moon shadow in the daytime sky. I thought it was worth a try; Akkana thought it should be possible. Starry Night said that a perfect event was going to happen this afternoon.

So at 4:30pm PST today (Oct 27), as the shadow of Io crossed Jupiter's meridian I was watching. But using my Meade 12" LX200 and my new Zeiss binoviewer and 19mm Panoptics I just couldn't see it. However with a 12mm Nagler and no binoviewer it was there! Not easy, mind you but definitely there. I could also see it in most of my other eyepieces (including the 19mm Pans). I finally saw it with the binoviewer, too, but it was MUCH more difficult. I guess that extra bit of light really matters sometimes.

The NEB and SEB were clearly visible, much easier than the shadow. I was having considerable difficulty focusing as the seeing was predictably horrible from my driveway in the middle of San Jose. The belts are so large that they're easy to see even when a little out of focus. Not so the tiny shadow.

Perversely, as the Sun set, I was taking my scope back inside. I had to watch the business news tonight :-(

Bill Arnett; last updated: 1997 Oct 19