The Observant Astronomer

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

Friday, September 29, 2006

Gloibal Varming

So now, apparently, we Jews are responsible for global warming too. An outfit called the "Coalition on the Environment and Jewish Life" dumped a pile of fliers in shul the other day exhorting Jews to change their light bulbs. After all,
the Jewish community has an intrinsic responsibility to respond to the daunting environmental problems confronting us and future generations.

So, no longer are we to be permitted to use incandescent light bulbs. It is now, according to the unpronounceable COEJL, a halachic imperative to only use "energy efficient, cost effective compact fluorescent light (CFL) bulbs".

"If not now, when?" they ask. And then answer that we're to do this "as a community" on Hanukkah. So, get going and apply to your "institution's Point Person" for your quota of CFLs and, come Hanukkah, replace your incandescents with CFLs. One per night, I suppose, would be in order. This way we can become "energy observant"!

Their enthusiasm is misplaced, however, in that they are ignoring the real Jewish contribution to global climate change: Shabbos. Never mind the energy wasted by light bulbs. Consider the energy wasted by leaving on the stove and other appliances for 26 hours straight. And for what? After the cholent has come off, that stove is likely heating up nothing but the blech. And if your household is anything like mine, there are too many burners on all night anyway, since the main objective is to keep the food hot for the Shabbos evening meal. Waste, waste, waste. Further, consider the amount of carbon dioxide and other toxins being given off by the Shabbos candles. An incredibly convenient suggestion in this regard is to "replace an outdoor light fixture with one that has a motion-detector" on the first day of Hanukkah, which, fittingly, is on Shabbos this year. Incomplete combustion of wax candles is considered to be a major Jewish contribution to global CO2 production. Never mind the methane produced as a result of kiddushes and cholent beans. So, once we've replaced all our light bulbs, as our next contribution to "protecting creation", we'll be called upon to sit in the dark and eat cold food one day a week. The Karaites will be pleased to see their position justified by the Rabbinics at last.

Monday, September 25, 2006

Shuttle on the Sun

Click on the link for a spectacular image of the Shuttle Atlantis and the International Space Station silhouetted against the Sun.

(hat tip to Jay Manifold who estimates it was taken with a 13cm telescope)

Today's picture shows the reality behind the infamous "Face on Mars". Is that a road going up the side?

Friday, September 22, 2006

Chasiva v'chasima tovah 5767

I seem to be getting a lot of hits at the moment from people googling "chasima". I don't know if this is what you were expecting, but if not, I don't know what that was, and probably don't want to know either. As in, for existence, "goth". One Shabbos afternoon, not so long ago, a young woman sitting on her front asked me as I went by if I was a "Goth". I stopped dead and asked for a repetition of the question, wondering what she was talking about. And was she particular about my being a Visigoth or an Ostrogoth? I was tempted to just reply, "No, I'm a Vandal", but decided to just say no and keep going. I found out something more about gothkeit from the events in Montreal last week. So, I'm not googling chasima, if you don't mind.

The shul I daven on weekdays has two luachs on the wall giving details of the customs of the year. One from Colel Chabad and one from Ezras Torah. And yes, they do get confused from time to time over which minhag to follow. Anyway, the two end off with some wishes for the new year. One has
ולשנה טובה נכתב ונחתם שנה גאולה וישועה אמן
and the other
תחל שנה וברכותיה
ותשובה ותפלה וצדקה מעבירין את רועה הגזירהס
with the last line in real big letters. The next year's luach starts exactly the same way. So, whatever your viewpoint, may you and yours, and all Yisroel, be blessed in the new year with a good, sweet, and healthy year, a year of peace, and a year of redemption.

Tuesday, September 19, 2006

The problematic election of 2016

(Warning: Really obscure Canadian content)
Debated yesterday* for the first time in Ottawa is Bill C-16, An Act to amend the Canada Elections Act which introduces fixed election dates for Canadian Federal Elections. The date would be the third Monday in October in the fourth year after the previous election, except where it is "in conflict with a day of cultural or religious significance or a provincial or municipal election" in which case we pick an alternate day which "must be either the Tuesday immediately following the Monday that would otherwise be polling day or the Monday of the following week."

All well and good, except that we'd better hope that no election comes due in 2016, 2043, 2073, 2100, or 2114 in the next century or so. Otherwise, despite their best intentions, observant Jews will still have to vote in advance. For in all those years, election day is the first day of Sukkot, and neither alternate day is any more suitable.

*It is amusing, in light of the events of last May, to see the Liberals worrying about the definition of "confidence".)

Thursday, September 14, 2006

The largest dwarf planet has been named

OK, no more references to "Xena". 2003 UB313 and its satellite now have official IAU approved names to go along with the official number given last week. The largest dwarf planet is now Eris and its moon is Dysnomia. Considering the ruckus it caused, a fitting name.

Monday, September 11, 2006

Aluminum & Mercury

Over at Treppenwitz they're being kept at night by thoughts ofaluminium and mercury. These two elements keep astronomers up at night too.

It's much easier to make a large aperture telescope with a mirror than with a lens. You only have to get the curvature right on one surface, it doesn't have to be perfectly clear, and it is a lot easier to support a big lump of material from behind, than by holding on to a thin edge. First, mirrors were made of solid metal. Speculum, a copper-tin alloy, being the favourite. Speculum corrodes and needs to be repolished every few months, so a big telescope would have two such mirrors, each to be used while the other was being cleaned up. In the 19th century, after the technology had been developed to coat glass with uniform metal films, silver-coated mirrors were favoured. The main problem with silver is that it tarnishes. Silver oxide is black, as evidenced by your silver kiddush cups and candlesticks. So periodically, before the point was reached where the reflecting mirror wasn't, the entire mirror had to be pulled out of the telescope, the silver removed and a new coating deposited.

Aluminum cured this problem, and also is more reflective to boot. The technology to make aluminum mirrors arrived in the early 1930's and almost all reflecting telescopes now use this. Aluminum oxide, in large lumps, looks like this or this with a few impurities. Clear and hard, a perfect protective coating.

Mercury, as David notes, does this in, but there are mercury telescopes. Mercury is a shiny reflective metal; too bad it's a liquid. The trick is to put a thin layer in a rotating tub and make a Liquid Mirror Telescope. The largest is 6m across, and serious telescope makers are thinking about a 100m behemoth to be deployed on the Moon. The advantage is that a liquid mirror telescope is much cheaper to construct than a conventional telescope. The disadvantage is that it can only look up. But for the purposes of a telescopic survey, that's just fine.

Thursday, September 07, 2006

Defining "Planet" IV

I won't promise that this is the last posting on the topic, but two consequences of the IAU resolutions have come to my attention.

First, the Minor Planet Center, charged by the IAU to keep track of all the minor planets, have now decided that dwarf planets are to be given official numbers in the catalogue of "minor planets", since the first of them (1) Ceres, already has one. This doesn't preclude a separate catalogue, and scheme for dwarf planets, but they're trying to keep things tidy. So from now on it is (134340) Pluto.

Second, somebody in California legislature clearly thinks he could be doing something more useful than this. The question is whether all his "co-authors" are in on the joke.