(Crossposted to Jewschool.)
As many of you know by now, November 28, 2013, will be both (American) Thanksgiving and the 1st day of Chanukah! The possibilities are endless: deep-fried turkey; latkes with cranberry sauce and gravy; pumpkin sufganiot; I’m sure you have more in mind. This week an article by Jonathan Mizrahi on this calendar issue has been making the rounds. It has some excellent graphs illustrating both the rarity of Thanksgivukkah in our present era and the long-term drift of the calendar that will make Thanksgivukkah impossible in the future, but it somewhat overstates its primary claim that Chanukah and Thanksgiving are “a once in eternity overlap”. This FAQ answers some questions that this article has inspired in various other forums, and corrects a few nuances.
Many thanks to Stephen P. Morse for creating an excellent tool to answer calendar questions quickly (though if he’s reading this, I’d love to see the capability of going beyond 9999 CE, and of distinguishing between Adar and Adar I), and to Remy Landau for providing the raw data on the Rosh Hashanah drift (though if he’s reading this, what’s with the popup ads?).
If you have questions that aren’t answered here, we’ll try to answer them in the comments (and if there are a lot, we’ll put together a sequel).
1. What is causing the long-term drift in the calendar?
You’ll notice from Mizrahi’s graph that the Jewish holidays shift significantly from one year to the next (like seasonal variations in the weather), but also (on average) slowly drift later over long time periods (like climate change). The year-to-year shifts are because the Hebrew calendar is primarily a lunar calendar, and 12 lunar months are approximately 354 days – much shorter than the solar year of ~365.25 days. Without any correction, the Jewish holidays would continue to move ~11 days earlier every year. (This is what happens with the Islamic calendar, in which every year is 12 lunar months without exception, so over several decades the Muslim holidays traverse the entire solar year.) In order to keep the Jewish holidays roughly aligned with the solar year (so that Pesach is always in spring, etc.), an month is added every few years, so Jewish “leap years” have 13 lunar months instead. As the Greek astronomer Meton discovered, 235 lunar months (=19*12 + 7) are approximately equal to 19 solar years, so if we put the calendar on a 19-year cycle, and add an extra month to 7 out of every 19 years, it mostly works out.
BUT NOT EXACTLY. 235 lunar months add up to 6939 days 16 hours 595 parts. (In Jewish calendar math, “parts” are the basic subdivisions of an hour, instead of minutes and seconds. There are 1080 parts in an hour, so 595 parts is about 33 minutes.) In the Gregorian calendar, 19 solar years (on average) are 6939 days 14 hours 626 parts. That’s about a 2-hour difference. So the Jewish holidays (on average) shift about 2 hours later during each 19-year cycle, which adds up to a full day every 231 years.
2. Is this an issue of Julian vs. Gregorian calendars?
Not really. 19 Julian years (on average) are 6939 days 18 hours. So if the Gregorian calendar is closest to the actual solar year, the Jewish calendar is doing better than the Julian calendar at approximating it (but still not well enough). (Think of it this way: By definition, the Julian calendar deviates from the Gregorian calendar by 3 days every 400 years. The Jewish calendar deviates by slightly less than 2 days in the same time period.)
3. But there’s some mechanism in place to correct this drift before it gets out of hand, right?
Nope. If no action is taken, the Jewish calendar will continue to drift later and later, until Pesach is in summer, Rosh Hashanah is in winter, etc. And it’s not clear how any action could be taken, since there’s no Jewish pope or Sanhedrin or any sort of body empowered to act on behalf of the whole Jewish people. But on the bright side, (as Mizrahi mentions) if we wait tens of thousands of years, we’ll loop all the way around to where we started.
The Catholics do have a pope, and so even though Easter is on a similar 19-year cycle, they’ve instituted corrections to keep it from drifting. Easter and Pesach usually coincide, but in the years when they’re a month apart instead, let’s just say it’s not Easter’s fault.
So far, Nobel week 2011 has been Good For The Jews, with Jewish scientists among the winners in 3 out of 3 prizes. Following Beutler and Steinman on Monday in Medicine, and Perlmutter and Riess yesterday in Physics, today’s winner in Chemistry is the Israeli materials scientist Dan Shechtman of the Technion. This is Israel’s second chemistry prize in 3 years; Shechtman follows Ada Yonath of the Weizmann Institute, who won in 2009 for her work on the structure of the ribosome.
What did Shechtman win for? He revolutionized the field of crystallography by discovering quasicrystals, crystals whose atoms form a pattern that never repeats. The story of the discovery is pretty amazing; I recommend reading the whole thing from the Nobel website.
When Shechtman told scientists about his discovery, he was faced with complete opposition, and some colleagues even resorted to ridicule. … The head of the laboratory gave him a textbook of crystallography and suggested he should read it. Shechtman, of course, already knew what it said but trusted his experiments more than the textbook. All the commotion finally led his boss to ask him to leave the research group, as Schechtman himself recalled later. The situation had become too embarrassing.
In the coming days, we’ll see whether the sweep holds up for Literature, Peace, and Economics.
Mazal tov to Saul Perlmutter (Lawrence Berkeley National Laboratory), Brian Schmidt (Australian National University), and Adam Riess (Johns Hopkins University; Space Telescope Science Institute) for winning the 2011 Nobel Prize in Physics for their discovery that the universe is not only expanding, but accelerating!
Apart from the Woody Allen clip, why is this story on Jewschool? Because Perlmutter and Riess are both Jewish! They are the first Jews to be awarded a Nobel Prize since… yesterday, when Bruce Beutler and Ralph Steinman z”l won the Nobel Prize in Medicine (along with Jules Hoffmann) for their work in immunology. They are also the first Jewish physics laureates since Roy Glauber in 2005.
Mazal tov to Prof. Elon Lindenstrauss of Hebrew University and Princeton University, who just became the first Israeli to win the Fields Medal! The Fields Medal, awarded this week in India at the International Congress of Mathematicians, is often called the Nobel Prize of mathematics (there is no Nobel in math), but unlike the Nobel Prizes, it is only awarded every 4 years, and only to people age 40 and under.
Lindenstrauss won the prize “for his results on measure rigidity in ergodic theory, and their applications to number theory”. “Er-WHAT-ic theory?”, you may ask. The official release explains:
Upon setting out to write this dvar Torah, I had grand visions of talking about the halakhic status of coed toilets. If a woman is ritually unclean, how can other members of her family use the same toilet, for example?
There was going to be a blow-out Foucauldian analysis of the halakhic sources, followed by a lengthy exegesis on Melanie Klein’s partial object; Kohut’s narcissistic transference, and Freud’s paranoia “syllogism” as taken up by Lacan. And then the ground-breaking revelation that we have been/are currently/always will be sinning.
It was going to be fabulous.
Perhaps fortunately for you, Masechet Niddah, Masechet Khullin, and Masechet Keilim (11:2) took me to school. Once again. We can use the same toilet as someone who is ritually unclean because the toilet is “מחובר לקרקע” (it is connected to the ground)—this is the loophole. (For those following at home, this is the same term used in reference to mikvaot, or ritual bath pools.) Furthermore, I learned that in our times–i.e. post-Temple times–we are all tamei met already, and thus this is a non-issue.
Now that we’re all breathing comfortably…
I will tell you, instead, about how I first learned about sex. (What does this have to do with tazria metzorah, you ask? Just wait. You’ll see.) More »
(Crossposted to Mah Rabu.)
We’ve been reporting about the contest to name the planets Uranus and Neptune in Hebrew, as part of the International Year of Astronomy.
As ADDeRabbi reports, the winners were announced today at a ceremony at the Hebrew University of Jerusalem. (As a finalist, I was invited to the ceremony, but was unable to attend since I was in the wrong country.) And the winners are…. “Oron” for Uranus, and “Rahav” for Neptune! Mazal tov (as it were) to ADDeRabbi, who was one of the entrants who submitted Rahav! My submission, Shahak (for Uranus) had to settle for runner-up; I suspect that Meretz stuffed the ballot box.
To infinity and beyond!
(Crossposted to Mah Rabu.)
Back in January, we posted about the contest to come up with Hebrew names for the planets Uranus and Neptune, as part of the International Year of Astronomy. Some of you may have submitted entries. The finalists have now been announced!!!
The two contenders for the planet hereunto known as Uranus are:
- Oron – “The name means ‘little light’ , and it hints at the faint light of the planet as seen from Earth due to its great distance from the sun. The name Oron sounds similar to the foreign name [Uranus] and helps in remembering it.”
- Shahak – “The proposal follows the meaning of the name Uranus, the name of the god of heaven. In Hebrew tradition there is no parallel name for the god of heaven (besides the name of the Supreme God). The word ‘shehakim’, in rabbinic literature, indicates one of the seven firmaments, and is also found in our Hebrew, and thus the singular form Shahak is appropriate as a proper name for the planet.”
And for Neptune:
- Rahav – “The proposal follows the meaning of the name Neptune – the name of the god of the sea. The name parallel to it in Jewish tradition is Rahav – the name of the master of the sea. Thus, for example, the Babylonian Talmud explains the verse [JPS translation: 'By His power He stilled the sea; By His skill He struck down Rahab'] (Job 26:12) as describing the victory of the master of the sea. The name Rahav bears mythological connotations like the Latin name.”
- Tarshish – “This is the name of one of the stones of the breastplate [Exodus 28:20] whose Aramaic translation (Onkelos) is ‘the color of the sea’ (among other opinions) — and this is also Neptune’s color as seen from Earth — bluish-green. ‘Tarshish’ is also connected to the sea in its other biblical use: the name of a place on the shores of the Mediterranean Sea, whose identification is not certain (recall the flight of Jonah the prophet to Tarshish). And on the phrase ‘the ships of Tarshish’, Rashi says ‘Tarshish – name of a sea’. In rabbinic literature and in liturgical poetry ‘Tarshish’ is a synonym for sea, and also a name of angels. Thus the name Tarshish combines the connection to the sea (like the Latin name) and the mythological foundation (angels).”
I was one of 25 entrants (including an 8th-grade class in Netanya) who submitted “Shahak” for Uranus, and congratulations to ADDeRabbi, one of 15 people who submitted “Rahav” for Neptune!
So the next step is voting! The vote is being conducted online. Unfortunately for those of us outside Israel, the ballot asks for a te’udat zehut (ID number), so only Israeli citizens can vote. If you’re eligible, vote!!! The fate of two planets is in your hands. The winners will be announced in December at the conclusion of the International Year of Astronomy.
…of earth. Okay, so yahoo isn’t exactly what I’d call a usual source of news (or actually, any source at all, really), but what the heck, I happened across this…
Seems that scientists in Israel have discovered the oldest surface of the earth… 1.8 million, to be exact. The next nearest is in Nevada.
Hey pretty cool… I mean, hot. yeah.
One year ago, BZ alerted us that Birkas Hachamah would be coming up in one solar year. Today was that day.
If your morning was at all like mine, it started with an astronomy lesson, around 5:30am, while standing outside in a huddle of shivering Jews. Through telescopes, we looked at the planets, all of which were visible this morning (except for Saturn, which had already set). We davened shacharis inside as the sun rose above the horizon and warmed up the beis midrash. Then we had a siyyum l’bechorim and bechoros so that those of us who are first borns wouldn’t have to fast today. Fittingly, the siyyum was on Masechet Hachamah, which meant we had more astronomy lessons, as well as some math, physics, history, and theology. Back outside for Birkas HaChamah, praising G!d for having created the sun (and everything else), and for burning chometz.
… All this before 8am. A full morning indeed!
I’ve been impressed by the number of tweets and Facebook updates related to Birkas Hachamah. People gathered on college campuses and beaches, in parks and stadiums. Did you do anything? Where? What would you suggest doing similarly, or changing, for Wednesday, April 8, 2037?
Let’s take a break from all the Gaza news and remind ourselves that the universe is much, much larger than these conflicts. 2009 has been declared the International Year of Astronomy (sponsored by the International Astronomical Union and UNESCO, along with organizational associates around the world), commemorating the 400th anniversary of the first astronomical observations with a telescope (by Galileo) and the publication of Kepler’s laws of planetary motion, two events that could be considered the birth of modern astronomy. The IYA is being celebrated with numerous events around the world, including a contest to come up with Hebrew names for the planets Uranus and Neptune!
You see, the first 5 non-Earth planets in our solar system are visible to the naked eye and were well-known to ancient astronomers. Therefore, they each have long-standing Hebrew names: Mercury is Kochav, Venus is Nogah, Mars is Ma’dim, Jupiter is Tzedek, and Saturn is Shabbetai. However, Uranus and Neptune were discovered in 1781 and 1846, and when Hebrew was revived as a spoken and scientific language, no Hebrew names were chosen; Hebrew speakers (like speakers of most languages) have referred to these planets by the name of a Greek and a Roman god. No more. The science division of the Academy of the Hebrew Language has announced a contest to select authentic Hebrew names. (Pluto has been demoted from planet status, and is therefore not included in the contest.)
Submissions will be accepted any time until Lag Ba’omer (May 12). Finalists will be chosen by a panel of Israeli astronomers and Academy members, and the final decision will be put to a public vote. The winners will be announced over Chanukah.
Be creative! I’ve already put in my submission (though I’m not going to tell you what it is until the finalists are announced). And good luck!
(Crossposted to Mah Rabu.)
One (solar) year from today, Wednesday, April 8, 2009, is birkat ha-chamah, the blessing for the sun that is said only once every 28 years!
Why every 28 years?
The short version: It’s based on bad science, but it’s still cool to have something like this that only happens a few times per lifetime. We should brainstorm about how to take advantage of this opportunity!
The longer version:
According to Reuters, a new study from researchers at McGill University, published in The Journal of Sexual Medicine, have revealed what lots of people have known all along: circumcision has no effect on sexual sensation.
There’s lots of things I could say here, but the truth is, this study doesn’t much matter. For those who are determined to stop circumcision, this won’t make any difference – they’ll go on touting the flawed studies they’ve been using (one big problem that I noted a while back with those studies- they relied on men circumcised as adults, and also several of them on men who were unhappy with their circumcisions. Um, durr) and for those who are commanded to circumcise, well as they ought, they’ll go on circumcisiing. Because in the end, that’s the reason one does it. Not because it’s healthier for their sexual partners, or because it lowers the (relatively miniscule anyway) risk of penile cancer. Circumcision for Muslims and Jews is because God commanded it. That’s it. Move along now.
Today: What’s kosher
181. “The following you shall abominate among birds — they shall not be eaten, they are an abomination:” (Leviticus 11:13) = followed by the whole list of forbidden birds
182. “Anything in the seas or in the streams that has no fins and scales, among all the swarming things of the water and among all the other living creatures that are in the water — they are an abomination for you, and an abomination for you they shall remain: you shall not eat of their flesh and you shall abominate their carcasses.” (Leviticus 11:10-11)
183. “All winged swarming things are unclean for you; they may not be eaten.” (Deuteronomy 14:19)
184. “All the things that swarm upon the earth are an abomination; they shall not be eaten.” (Leviticus 11:41) = swarming creatures that reproduce normally
185. “You shall not make yourselves unclean through any swarming thing that moves upon the earth.” (Leviticus 11:44) = swarming creatures formed by spontaneous generation (I’m just reporting what the Rambam says)
186. “You shall not eat, among all things that swarm upon the earth, anything that crawls on its belly, or anything that walks on fours, or anything that has many legs; for they are an abomination.” (Leviticus 11:42) = worms that come out of fruit
187. “You shall not draw abomination upon yourselves through anything that swarms.” (Leviticus 11:43) = water creatures
188. “You shall not eat a carcass.” (Deuteronomy 14:21) = an animal that died by means other than kosher slaughter
189. “Its flesh shall not be eaten.” (Exodus 21:28) = an ox that gores someone and is executed
190. “You must not eat flesh torn by beasts in the field.” (Exodus 22:30) = or any animal (even if slaughtered properly) that has any of the defects that render it tereifah or “treif”
191. “You must not consume the life with the flesh.” (Deuteronomy 12:23) = don’t eat any part of a living animal
192. “Do not eat any blood.” (Leviticus 3:17)
193. “Do not eat any cheilev.” (Leviticus 3:17) = forbidden fat
194. “That is why the children of Israel to this day do not eat the thigh muscle that is on the socket of the hip, since Jacob’s hip socket was wrenched at the thigh muscle.” (Genesis 32:33)
195. “Don’t cook a kid in its mother’s milk.” (Exodus 23:19) = don’t eat meat with milk
Conservative author Charles Murray begins his piece “Jewish Genius” in Commentary thusly:
Since its first issue in 1945, COMMENTARY has published hundreds of articles about Jews and Judaism. As one would expect, they cover just about every important aspect of the topic. But there is a lacuna, and not one involving some obscure bit of Judaica. COMMENTARY has never published a systematic discussion of one of the most obvious topics of all: the extravagant overrepresentation of Jews, relative to their numbers, in the top ranks of the arts, sciences, law, medicine, finance, entrepreneurship, and the media.
The article begins with a historical perspective, making a case that post-haskalah (enlightenment), Jewish involvement and accomplishment in the brainy parts, namely arts and sciences (notice we’re not very good at sports) of the broader society has been vastly disproportionate to our meager numbers (“our” not including Murray, who isn’t Jewish).
The NY Times reports,
Some animals are surprisingly sensitive to the plight of others. Chimpanzees, who cannot swim, have drowned in zoo moats trying to save others. Given the chance to get food by pulling a chain that would also deliver an electric shock to a companion, rhesus monkeys will starve themselves for several days.
Biologists argue that these and other social behaviors are the precursors of human morality. They further believe that if morality grew out of behavioral rules shaped by evolution, it is for biologists, not philosophers or theologians, to say what these rules are.
Moral philosophers do not take very seriously the biologistsâ€™ bid to annex their subject, but they find much of interest in what the biologists say and have started an academic conversation with them.
So if monkeys have morals, what’s our excuse?