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Questions tagged [astronomy]

The study or observation of objects or phenomena outside the Earth, including the Sun, Moon, planets, and stars.

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1 answer
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Is there an exhaustive list of astronomical/environmental events for which there are blessings?

Inspired by: What Bracha should you say on a Hurricane? What Blessing Does One Make on a Solar Eclipse? Bracha for the transit of Venus? What b'racha do you say on seeing the Aurora Borealis (if ...
Isaac Moses's user avatar
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18 votes
7 answers
1k views

How did the moon shrink?

The Bavli, Chulin 60:2, says (in my own loose translation): Rabbi Shim'on ben Pazi noted a contradiction: [B'reshis 1:16] says, "God made the two big luminaries" and "the big luminary… ...
msh210's user avatar
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13 votes
1 answer
486 views

What defines "on this earth" from a halachic standpoint?

Rabbi Ben-Zion Firrer asked whether Torah Law must be observed in space, since Deuteronomy 12:1 says one should follow the Commandments "all of the days which you are alive on this earth." What ...
SAH's user avatar
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8 votes
1 answer
233 views

New date at sunset: question on Sifse Chachamim

Avoda Zara 25 cites a difference of opinion as to how long the sun stood still for Y'hoshua: twelve hours, twenty-four, or thirty-six. According to those who say twelve or thirty-six, the sun finally ...
msh210's user avatar
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4 votes
2 answers
298 views

Good and Bad Omen - on something that can be calculated in advance

Inspired by Why make a bracha on an earthquake but not on an eclipse? When something can be predicted in advance to an exact moment - for example an eclipse which Chazal say it is a bad Omen (Sukkah ...
Gershon Gold's user avatar
18 votes
2 answers
3k views

What Blessing Does One Make on a Solar Eclipse?

What Blessing Does One Make on a Solar Eclipse? I will be in Nevada next week and would like to make a blessing over the May 21 Solar Eclipse. Thanks!
Pesach David's user avatar
15 votes
5 answers
1k views

Permissibility of images of celestial bodies

There is precedent in halachah that one may not create images of celestial bodies such as the moon and stars; see here for background. This is derived in the Gemara from the pasuk "Do not make [images ...
yitznewton's user avatar
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9 votes
3 answers
2k views

Is the midrash about the moon and sun being the same size intended literally?

The Rambam in his introduction to perek Chelek discusses midrashic literalist, and classifies different approaches of different groups to midrash. He writes: You should know that as to [...
josh waxman's user avatar
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7 votes
3 answers
966 views

Eclipse of the moon, bad sign for the Jews

Tonight, December 20, 2010, there will be a full lunar eclipse visible from North America and many other areas. I recall there is a Gemara that says that a lunar eclipse is a bad omen for the Jews as ...
Gershon Gold's user avatar
0 votes
3 answers
1k views

When did Hashem stop the sun?

As in the time of Milchemes Ay, Hashem stopped the sun for 36 hours. Where else in Tanach did it happen? I need more then one.
Curious's user avatar
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4 votes
3 answers
574 views

Stars are living creatures?

the Rambam in yesodei torah says that stars are creatures with intellect. how do we reconcile this with modern science which says that they are merely inanimate balls of hydrogen and helium gas.
michael's user avatar
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12 votes
4 answers
986 views

Plants before the Sun in the Order of Creation

Why does plant life precede the Sun in the order of creation given that plants need the Sun to do photosynthesis?
הראל's user avatar
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12 votes
2 answers
586 views

Latest shabbat not longest day...?

I was under the impression that the longest day was June 22nd, and yet, year after year- the latest time for candle lighting takes place about a week and a half after that. Intuitively, the latest ...
user avatar
12 votes
6 answers
1k views

How to Resolve Kiddush Levana and Celestial Worship, (Avodas Kochavim)?

In general Kiddush Lavanah has always seemed to me to be akin to "Avodas Kochavim" - so does anyone know of a satisfying answer that works with Occam's razor? More specifically: We say Just as I can ...
Aaron Greenberg's user avatar
10 votes
6 answers
13k views

What is the firmament?

In Genesis 1:6-8 the firmament and its creation are mentioned for the first time: And God said: 'Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.' ...
Gabriel12's user avatar
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10 votes
4 answers
840 views

Why make a bracha on an earthquake but not on an eclipse?

According to this page, Chaza"l intentionally omitted solar and lunar eclipses from the list of natural phenomena upon which we make a bracha. The following explanation is given: The Hebrew term ...
SAH's user avatar
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8 votes
3 answers
250 views

Depicting a constellation

Assuming the intention is at least partly for educational purposes, Is it mutar to arrange star stickers in the form of actual constellations (say, on a ceiling) or is that included in the prohibition ...
Loewian's user avatar
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8 votes
4 answers
543 views

How accurate is the Molad?

To the best of my knowledge the Molad is every 29.5 days + 793 Chalakim. Is there any information showing if the current Molad calculation is accurate scientifically? If it is off by how much is it ...
Gershon Gold's user avatar
5 votes
0 answers
1k views

Minyan, netz hachamoh, and precision in time

There are halachic sources that discuss the importance of davening shemona esrei at netz (at sunrise), some of which state that it is preferable to daven at netz over davening with a minyan (at least ...
Isaac Kotlicky's user avatar
5 votes
2 answers
5k views

What time is sunset?

Is sunset (Shkiya) the time the sun hits the horizon or when it sunk completely below it? What about sunrise?
ertert3terte's user avatar
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11 votes
2 answers
307 views

Bracha for the transit of Venus?

Venus is transiting today for the last time until 2117 (or 5878, if you prefer). Is there a specific bracha that should be made upon witnessing this spectacular event?
SAH's user avatar
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9 votes
1 answer
1k views

What b'racha do you say on seeing the Aurora Borealis (if any)?

If one is so lucky as to see the Aurora Borealis (northern lights) or its southern equivalent, does one say a b'racha? If so which one? I've heard that oseh ma'aseh v'reishit applies to comets and ...
Monica Cellio's user avatar
8 votes
1 answer
365 views

Is there any evidence of time-zones in Talmud? (Tanaim and Amoraim only)

There are many verses in the Talmud, Midrash and Siddur that state that the sun and moon rise and set through gates in the firmament. This would imply that there are no time-zones. To this world view ...
Ronen's user avatar
  • 389
8 votes
2 answers
2k views

Magen Avraham - Practically no Plag HaMinḥah or just no Plag HaMinḥah in winter?

Calling all science and math-oriented Judaism.SE-ers! According to the website MyZmanim.com, today's Halachic times where I work are as follows (only a handful of times are shown because the question ...
Seth J's user avatar
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8 votes
1 answer
959 views

What does Maimonides say about geocentrism?

I have read that Maimonides described the universe in a geocentric fashion, but I have not been able to find the specific passages to which they refer. What does Maimonides say about geocentrism?
AdamRedwine's user avatar
7 votes
4 answers
223 views

How to care about the molad

I have read the great answers to Purpose of announcing Molad and understood that the halakhic reason to know the molad is to know what the Sanhedrin would know when they declared a new month. But ...
Charles Koppelman's user avatar
6 votes
1 answer
104 views

Counting years according to the solar calendar

I once heard there is an opinion in Rishonim (maybe Gaonim?) that says we count ones years of life according to the solar calender. So for example a boy would become bar mitzvah when he would turn 13 ...
Yehoshua's user avatar
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4 votes
3 answers
423 views

Significance of number 613 regarding the mitzvot

According to the Talmud (Makos 23b) "Moshe received 613 Mitzvos. They are 365 Lavim (negative commandments), corresponding to the days of the (solar) year, and 248 Mitzvos Aseh (positive commandments),...
ray's user avatar
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4 votes
1 answer
656 views

Jewish Sunrise and Sunset

How can one calculate Jewish sunrise and sunset? I'm not necessarily asking for a formula. Just wondering if there's a difference between Halachik rise/set and what the world considers [e.g. science] ...
yydl's user avatar
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4 votes
1 answer
475 views

Sukkos 2a ~ Reality shows the need for 13-אמות while the Gemara states that the smallest Sukkah is enough?

ר׳ זירא says that a Sukkah that is lower than 20-אמות, the סכך is the one blocking the sun and creating the shadow, not the walls, and therefore the Sukkah is kosher, like it says in the פסוק ״וסוכה ...
Yid's user avatar
  • 179
3 votes
1 answer
353 views

Aurora Borealis in Midrashim

We see many fascinating works of Hashem around the world and one of which is Aurora Borealis. Do our midrashim or books on mysticism have anything to say about its origin or anything related to it?
Rh Haokip's user avatar
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0 votes
1 answer
159 views

Parameters of the bad omen for eclipses

The Gemara in Succah 29a says that solar eclipses are bad omens for the nations, while lunar eclipses are bad omens for the Jews. The Gemara compares an eclipse to a king who leaves his guests sitting ...
DonielF's user avatar
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-2 votes
2 answers
234 views

Why did G-d create the Earth spherical?

I hope nobody questions the fact of the spherical Earth. Just as spherical as all other celestial bodies. Many argued whether we knew this fact or not, but I don't recall that those who claim we ...
Al Berko's user avatar
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