Are You Ready for the Longest Lunar Eclipse this Century?

On Friday July 27 and into the early hours of Shabbat on July 28, there will be a total lunar eclipse. Now, these are not that rare - elsewhere we discussed the one that occurred on the first night of Sukkot (September 27) 2015. But what makes this one special is that it will be the longest lunar eclipse of this century. It will be visible for 103 minutes. It will also be a little different from that 2015 Sukkot eclipse.  That one occurred when the moon was at its closest to the earth; this one will occur when the moon is at its furthest point from earth.  So the moon will be a little smaller. You can see the relative differences is size of the two below.

Courtesy of  NASA .

Courtesy of NASA.

As we've noted before, a solar eclipse can only occur at the start of  a Hebrew month, as the moon gets between the sun and the earth.  A lunar eclipse is also linked to the Jewish month, and can only occur around the 15th day of the month, when the moon is full.  As the earth passes between the sun and the moon, its shadow is cast onto the moon, resulting in an eclipse.

 So why don't we see a lunar eclipse every month? The answer is simple. The moon's orbit is inclined at 5 degrees from the sun-earth plane, so that each month the moon may be slightly above, or slightly below that plane. And a lunar eclipse will occur only when the three bodies line up on the same plane.  

The Great shabbat Lunar Eclipse of the 21st century

The figure below (from here) shows when and how much of the eclipse you will be able to see.  As you can see, this eclipse will not be visible anywhere over North America. Which seems only fair since North America had its own spectacular solar eclipse last year, and didn't share that with the rest of the world.

Screen Shot 2018-07-24 at 12.50.41 PM.png
From  here

From here

But elsewhere there are great opportunities to get a good view. Here are some:

 Jerusalem London Paris Sydney Mumbai
Duration 6 hours, 13 mins, 51 sec 3 hours, 39 mins, 22 sec 3 hours, 59 mins, 37 sec 3 hours, 40 mins, 40 sec 6 hours, 13 mins, 51 sec
Duration of totality 1 hour, 42 mins, 56 sec 1 hour, 23 mins, 55 sec 1 hour, 42 mins, 56 sec 1 hour, 25 mins 12 sec 1 hour, 42 mins, 56 sec
Penumbral begins Jul 27 at 8:14:47 pm Moon below horizon Moon below horizon Jul 28 at 3:14:47 am Jul 27 at 10:44:47 pm
Partial begins Jul 27 at 9:24:27 pm Moon below horizon Moon below horizon Jul 28 at 4:24:27 am Jul 27 at 11:54:27 pm
Full begins Jul 27 at 10:30:15 pm Moon below horizon Jul 27 at 9:29:01 pm Jul 28 at 5:30:15 am Jul 28 at 1:00:15 am
Moonrise None Jul 27 at 8:49:16 pm Jul 27 at 9:30:15 pm Jul 28 at 6:21:44 am None
Maximum Jul 27 at 11:21:44 pm Jul 27 at 9:21:44 pm Jul 27 at 10:21:44 pm Jul 28 at 6:55:27 am Jul 28 at 1:51:44 am
Full ends Jul 28 at 12:13:11 am Jul 27 at 10:13:11 pm Jul 27 at 11:13:11 pm Moon below horizon Jul 28 at 2:43:11 am
Partial ends Jul 28 at 1:19:00 am Jul 27 at 11:19:00 pm Jul 28 at 12:19:00 am Moon below horizon Jul 28 at 3:49:00 am
Penumbral ends Jul 28 at 2:28:38 am Jul 28 at 12:28:38 am Jul 28 at 1:28:38 am Moon below horizon Jul 28 at 4:58:38 am

For the sake of our many new readers, and to refresh the minds of our others, let's take a re-look at what Judaism has to teach us about eclipses.


The Talmud on Eclipses

תלמוד בבלי סוכה דף כט עמוד א 

תנו רבנן: בזמן שהחמה לוקה - סימן רע לעובדי כוכבים, לבנה לוקה - סימן רע לשונאיהם של ישראל, מפני שישראל מונין ללבנה ועובדי כוכבים לחמה

תנו רבנן: בשביל ארבעה דברים חמה לוקה: על אב בית דין שמת ואינו נספד כהלכה, ועל נערה המאורסה שצעקה בעיר ואין מושיע לה, ועל משכב זכור, ועל שני אחין שנשפך דמן כאחד

Our Rabbis taught, A solar eclipse is a bad omen for idolaters; a lunar eclipse is a bad omen for Israel, because Israel reckons [its calendar] by the moon, and idolaters by the sun...

Our Rabbis taught, A solar eclipse happens because of four things:
1. When an Av Bet Din [head of the Rabbinic Court] died and was not properly eulogized;
2. If a betrothed girl cried out aloud in the city and there was no-one to save her [from being raped];
3. Because of homosexuality; and
4 If two brothers were killed at the same time.

That's what we have - four causes of a solar eclipse, and none for a lunar eclipse - we are just told that it is a "bad omen for Israel." And how does Rashi explain this passage?  לא שמעתי טעם בדבר  - "I have not heard any explanation for this." 


If we know that eclipses are regular celestial events whose timing is predictable and precise, how are we to understand Talmud in Sukkah, which suggests that an eclipse is a divine response to human conduct? We have already seen that Rashi was unable to explain the passage, but that didn't stop others from trying.  The Maharal of Prague (d. 1609) has a lengthy explanation which you can read here.  It goes something like this: "Yes, an eclipse is a mechanical and predictable event. But in truth, if there was no sin, there would be no eclipses, because God would have designed the universe differently, and in such a sin-free universe...there would be no need to design an eclipse." So the Maharal suggests that in a sin-free universe, the moon would not orbit as it does now, at a 5 degree angle to the sun-earth plane.  But where would the moon be? It couldn't be in the same plane as the sun and the earth, since then there would be an solar eclipse every month. If it were at say 20 degrees above the plane, then there would still be both solar and lunar eclipses, though they would be more rare. The only way for there to be no solar eclipses (in the Maharal's sin-free imaginary universe) would be for the moon to orbit the earth at 90 degrees to the sun-earth axis.  Then it would never come between the sun and the earth, and there could never be a solar eclipse. Perfect, except then there would never be a Rosh Chodesh, and the moon would always be visible. Oy.

יערות דבש דרוש י׳ב

יערות דבש דרוש י׳ב

Another attempt to explain the Talmud was offered by Jonatan Eybeschutz (d. 1764). In 1751 Eybeschutz was elected as chief rabbi of the Three Communities (Altona, Hamburg, and Wandsbek), and was later accused of being a secret follower of the false messiah Shabtai Zevi. In January 1751, Eybeschutz gave a drasha Hamburg in Hamburg in which he addressed the very same problem that the Maharal had noted: if a solar eclipse is a predictable event, how can it be related to human conduct? His answer was quite different: The Talmud in Sukkah is not actually addressing the phenomenon that we call a solar eclipse. According to Eybeschutz, the phrase in Sukkah "בזמן שהחמה לוקה" actually means - "when there are sunspots."

Inventive though this is, it is as implausible as the suggestion of the Maharal. In the first place, sunspots were almost (but not quite impossible) to see prior to the invention of the telescope. They were described in March 1611 by a contemporary of Galileo named Christopher Scheiner (though Galileo lost no-time in claiming that he, not Scheiner was the first to correctly interpret what they were.) Because sunspots were so difficult to see with the naked eye, it seems unlikely that this is what the rabbis in Gemara Sukkah were describing.

Christopher Scheine,  Rosa Ursina sive Sol  (Bracciai 1626-1630)

Christopher Scheine, Rosa Ursina sive Sol (Bracciai 1626-1630)

Second, according to Eybeschutz, sunspots "have no known cause, and have no fixed period to their appearance".  We can't fault Eybeschutz  for his first claim, but - even by the science of his day - his second was not correct. In fact both Scheiner and Galileo knew  - and wrote - that sunspots were permanent (at least for a while) and moved slowly across the face of the sun.

It's interesting to note that Galileo got very excited about the discovery that the spots moved across the face of the sun. This suggested (though it did not prove) that the sun itself was spinning. Galileo had also discovered that Jupiter was orbited by moons. Both of these discoveries now added further support to the Copernican model in which the Earth was spinning on its ownaxis, and was not the center of all the movement of objects in the sky. But Eybeschutz did not believe Copernicus was correct: "Copernicus and his supporters have made fools of themselves when they declare that the Earth orbits [the Sun]. They have left us with a lie, and the truth will bear itself witness that the Earth stands still for ever."  Eybeschutz wanted to have sunspots explain away a talmudic mystery, but he dismissed the evidence that they provided in other matters - namely, that the earth moves.

Don't worry America, there's another one coming....

For those who live in North America, the next opportunity to see a total lunar eclipse will be on January 20, 2019 - which is only a few months from now. But what you should start planning for is the next total solar eclipse that will be visible in North America.  Mark your calendars now. It will be on Monday April 8, 2024, two weeks before the start of Passover. So plan accordingly.

[Want even more? Then read this: The Great American Eclipse of 2017: Halachic and Philosophical Aspects.] 

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