Belt of Venus…

2006-09-05 07:50:30.000 – Jim Salge,  Observer

Undercast and Earth Shadow…

I don’t always like surprises, but even at 4:30 in the morning, a knock on the bedroom door doesn’t necessarily mean bad things at the Observatory. Sure sometimes, especially in winter, the late night wrap usually mean an instrument has failed and you have to go from deep sleep to -100F windchills, but these times are rare. Given the morning forecast when I went to bed though, I couldn’t rationalize why they were waking me up this morning.

“Jim … Undercast” was the only message I needed to get me moving though. I walked outside to the scene pictured at right…as well as calm winds, and relatively warm sunshine above!

There is one portion of the picture that I’d like to highlight this morning…the thin blue strip just above the horizon. This strip is called the ‘Belt of Venus’ and can sometimes be seen shortly after sunrise, or just after sunset. The strip is actually caused by the shadow of the earth itself, projecting out into the atmosphere. A bit of a confusing thing to picture, so here’s a nice schematic and explanation!

Jim Salge,  Observer