The Observant Astronomer

The passing scene as observed by an observant Jew, who daylights as an astronomer.

Saturday, January 28, 2006


I've refrained from posting about the election campaigns that concluded this week, but I do want to make one point. Anyone who thinks that Hamas's victory was about removing a corrupt regime is guilty of confusing the Palestinian election with the Canadian.

Thursday, January 19, 2006

Hubble Season

Just in case anyone is wondering if I fell off the Earth at perihelion, there is a good reason why blogging is even lighter than usual at the moment. It is the time of year when observational astronomers indulge in the annual ritual called HST Proposal. This is when we put aside all other work, or as much as possible, to come up with really good ideas to convice the Time Allocation Committees to give to our wonderful selves some of that rare and precious Hubble Space Telescope time. Competition is fierce for there are seven astronomers vying for every available HST orbit. (HST time is measured in orbits of the telescope about the Earth. Each one represents about 40 minutes or so of observing opportunity. The other half of the orbit, the Earth is usually blocking the target.) I'll have to explain another time (bli neder) why this is really important just now, but I've got to get back to work. Deadline is Jan 27th, so I should reappear after that.

Wednesday, January 04, 2006


Today the Sun and Earth are as close to each other as they ever get. Come 3 July they'll be as far apart as they get, i.e aphelion. Unlike the solstices and equinoxes, these events have no significance for the Jewish calendar. Nor do they take a stance on the centrism question. Further, we can clearly see that it is not now winter in the Northern Hemisphere because the Sun is further away.

But there is one practical effect of perihelion, for although the shortest northern day was back at the time of the winter solstice, at mid-northern latitudes this is the time of year with the latest sunrise. Call it vasikan season, when, if you are in the right place, even if you sleep in, you can still daven shacharis in the best manner, with Shema just before sunrise and Tefillah at sunrise.