The Observant Astronomer

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

Monday, October 31, 2005

Older than Methuselah

Methuselah may have lived a long time, but there are hints in the Midrash that the longest lived human was someone else.

Rashi brings down the following three, apparently sequential, passages from Breishis Rabbah 23:3-5 in his comments to Breishis 4:22-25:

1. On 4:22 "Naama, she is the wife of Noah."
2. On 4:24 Seventy-Seven, the explanation of Lamech's speech to his wives that they had dissociated themselves from him once they had fulfilled the mitzvah of procreation because of the decree against the descendents of Cain after seven generations.
3. On 4:25 Adam knew etc., he explains that Lamech took his wives to Adam Harishon to decide the matter. Adam says to the wives that it is not up to them to make calculations about Hashem's decrees. They respond, well in that case, why have you separated from your wife? Immediately we have that Adam again knew his wife and Shes was born.

1. (Premise) On the basis of the sequence of verses and the midrash that Lamech's wives had had children, that these children were the ones listed in 4:21-22, including Naama, and that they were already born before the events leading to 4:24.
2. (Fact) Shes was born in 130.
3. (Inference) Naama was born before 130.
4. (Fact) Noah's children were born in or after 1556.
5. (Conclusion) Naama was at least 1,426 years old when she had children and lived at least another hundred years to board the ark.

Saturday, October 29, 2005

Astronomical straight lines

It's been kind of cloudy and rainy here of late, so the re-appearance of the Sun on Simchas Torah led to the following exchange:

Not-me: Hey, what's that bright thing in the sky?
Me: Looks like a G2 dwarf.

Another oldie but goodie:

Not-me: What's that stuff coming through the window?
Me: H-minus continuum, mostly.

Public Service Announcement

I have been requested to make the following clarification regarding the available evidence for life anywhere in the universe beyond the Earth.

There isn't any. Not a scrap. Nothing credible at all.1

And no, it isn't being kept secret somewhere. You couldn't keep news like that quiet for more than a few days.

You may now resume your idle theological arguments in that regard.

1The only exception could be the claimed nanofossils in a meteorite from Mars found in Antarctica several years ago. This remains controversial, however.

Thursday, October 27, 2005

The importance of making distinctions

It is well known that the Snake gets Chavah (Eve) and Adam into trouble by playing on the inappropriate application of a gezerah (fence) around a mitzvah. Adam was commanded not to eat from the Tree of the Knowledge of Good and Evil. But Chavah tells the Snake that G-d had commanded them not to eat or touch The Tree on pain of death. So the Snake pushes her against the tree and, when she doesn't instantly drop dead, convinces her that eating the fruit is equally safe. At which point she gets Adam to eat too.

Now it is a known Rabbinic activity to enact precautionary prohibitions to keep us distant from sin. Many of the prohibited activities of Shabbos, for example, are of just this sort. Wasn't Adam doing exactly the same thing in adding the prohibition on touching the tree? But look again at what Chavah tells the Snake: "G-d said not to eat from or touch the tree." By attributing to G-d Adam's fence, Chavah is set up for trouble.

From this we learn that it is important to keep track of who prohibits what, and for what reason, lest a rabbinic instruction or a community standard be elevated to the level of a divine commandment, punishable by exclusion.

Friday, October 14, 2005

Reasons not to travel in a Chinese rocket

It seems that the Chinese have launched their 2nd manned space mission. Based on the linked CNN report, I have my doubts about the viability of the program.
China's Shenzhou 6 briefly fired its rockets to adjust its orbit early Friday as the spacecraft began its third day of a mission meant to help prepare for the eventual launch of a Chinese space station.

The maneuver was carried out after the capsule was found to have been dragged closer to the Earth by gravity, said the Web site of the Communist Party newspaper People's Daily. It said the "maintenance operation" lasted a few seconds, and there was no indication the crew was in any danger.
Or as an earlier version had it,
Astronauts discovered the craft had "slightly deviated from its designed orbit" and was moving a little closer to the Earth due to gravity, the official Xinhua News Agency reported.
Either this is a bad translation, or the Chinese press needs to learn some orbital mechanics. Either the capsule was delivered to the wrong orbit, or atmospheric drag was the culprit for lowering it. Gravity is keeping it going around. Which reminds me of an error I saw in a children's science encyclopedia according to which gravity stops at the altitude where spacecraft orbit, which is why astronauts float around, and then resumes around the orbit of the Moon. Here they seem to be dipping in and out of the gravity zone.
The official Xinhua News Agency said a new road to the landing site in grasslands of the northern Inner Mongolia region opened Friday as the space program prepared for the capsule's return.
Whew! I'm glad they got that finished in time, although I imagine the astronauts would have been more comfortable to see this before they launched.
Recovery crews spent Thursday practicing rescue work, launching helicopters to the primary landing area in the Inner Mongolia region, Xinhua said.
After all, the road wasn't open yet.
Communist leaders hope the manned space program's triumphs will stir patriotic pride, shoring up their standing amid public anger at corruption and a growing gap between rich and poor.

Chinese space officials say they hope to land an unmanned probe on the Moon by 2010 and want to launch a space station.
but since
The Shenzhou -- or Divine Vessel -- capsule is a modified version of Russia's workhorse Soyuz. China also bought technology for space suits, life-support systems and other equipment from Moscow, though officials say all items launched into space are made in China.
I do wonder what Russian hardware they plan on modifying for this purpose.

Thursday, October 06, 2005


This is one of those customs that just never seems to work for me.

Here we are, on one of the solemnest or most joyous days of the year. The Cohanim, heirs to the holiness of Aaron HaCohen, venture to the front of the shul to do their hereditary mitzvah and bless the congregation. Little children, down to babes in arm, crowd into the men's section, trying to find their fathers amongst the crowd of tallis wearing men. Your beloved children gather around you, and, with the conclusion of Modim, you extend your arms, lift the tallis, and protectively cover the wee ones as you listen to the ancient melody and holy blessing, mind filled with all the proper kevanahs. The children, down to the babe in arms, are still, quiet, nay, attentive, facing forward and answering "Amen" as appropriate.

Or, at least that's what's happening under everyone else's tallis.

Under mine, not a one of them is standing still. This one is sitting down. That one is pulling his sister's hair and she turns around to complain. The other one keeps ducking in and out, unable to keep still. The baby can't stand to be covered up under that stuffy wool blanket. I try to keep them covered, but they won't have it. All the movement is causing the tallis to fly all over the place, ending up heading to the floor as I grab it with the hand not holding the baby, as my yarmulke, pulled off by the tallis, heads down to the floor. The toddler has had enough, starts screaming, and heads out.

Ribbono shel Olam, forgive my unruly children. We need all the brochas we can get.

Monday, October 03, 2005

K'siva v'chasima tovah

May you be inscribed and sealed for a good, healthy, sweet, & prosperous new year.