Questions tagged [astronomy]

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

Filter by
Sorted by
Tagged with
1 vote
0 answers
60 views

Meaning / Significance of the Ring on planet Saturn

Shabbos and the planet Saturn are linked. I was wondering if anyone has a source for the ring(s) on the planet Saturn being a wedding between the Jews / Shabbos / Hashem? I heard this idea before but ...
Adam Kapelner's user avatar
2 votes
0 answers
73 views

Do Zmanim follow the city, or the Gavra?

Are halachic times for prayer, comencing Shabbos, ect. calculated according to a persons exact location or is there one "time-zone" for the entire city? And if yes, how would this apply for ...
Naftali Tzvi's user avatar
  • 1,703
0 votes
2 answers
135 views

Why are the planets so different from each other?

In Rambam's (originally Aristotelian) view the planets are heavenly bodies made of some magical crystal-like substance (i.e. Foundations_of_the_Torah.3.1). After we examined some of them, they turned ...
Al Berko's user avatar
  • 25.7k
1 vote
0 answers
84 views

What rabbis did explicitly deal with Heliocentrism (accepted or rejected)?

Following the closed question "whats-the-earliest-acknowledgment-of-heliocentrism", I'm looking for any rabbinic sources that explicitly deal with heliocentrism.
Al Berko's user avatar
  • 25.7k
3 votes
2 answers
136 views

Measuring Moon's elevation in units of length

Rosh Hashanah 24a: The Sages taught in a baraita: If one witness says that he saw the moon two plow handles high above the horizon, and the other one says it was three plow handles high, their ...
sds's user avatar
  • 1,299
0 votes
2 answers
242 views

Why does plant life come after the earth, waters and the firmament, but before the planets?

This question only addresses the blueprint of the creation as described in the first chapter of Bereshit. It does not address the sequence of the actual creation, as described in Bereshit 2, or the ...
Al Berko's user avatar
  • 25.7k
4 votes
1 answer
472 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
107 views

Meaning of Monen in Kabbalah

I came across the term "monen" but have been unable to find much information on it in scholarly or scriptural sources. The main information online appears to be a kabbalah-related stub on ...
Benny's user avatar
  • 31
0 votes
2 answers
843 views

What is the relation between the month Nisan and the spring equinox?

I'm searching for the relation between Nisan and the spring equinox according to Scripture. I know of the texts Genesis 1:14, Exodus 12:2-3, Leviticus 23:15 and Deuteronomy 16:1. I find multiple ...
Jan's user avatar
  • 109
2 votes
0 answers
75 views

A beracha on the "Great conjunction"?

Tonight (or earlier tonight in Israel) the planets Jupiter and Saturn come so close that one might think that they are a single star. Is this occasion to say the beracha of עושה מעשה בראשית? It is not ...
Mordechai's user avatar
  • 3,463
4 votes
1 answer
385 views

How to observe Shabbat on Mars

Inspired by this question. The Martian day is 24 hours, 37 minutes long. After approximately 39 Martian days, 40 days have passed on Earth. As a Martian colonist, should I rest every seventh Martian ...
dotancohen's user avatar
1 vote
1 answer
137 views

How can constant creation of new stars explained theologically?

"... we get on average about one new star per year, and one star dying each year as a planetary nebula in the Milky Way.... therefore there are about 275 million [born] per day, in the whole ...
Al Berko's user avatar
  • 25.7k
1 vote
3 answers
269 views

Has the number of the tribes of Israel anything to do with the universe/stars/planets?

Has the number of the tribes of Israel anything to do with the universe/stars/planets? Maybe the other way around? Is there anywhere in the Talmud or tradition that talks about this question (not ...
CreativeNorthWay's user avatar
-4 votes
1 answer
147 views

Why did G-d create everything important off-center?

I hope not to argue that the Heliocentric view is true as is our current understanding of [our position in] the Universe, the Earth is rotating around the Sun, that is rotating around the center of ...
Al Berko's user avatar
  • 25.7k
-2 votes
2 answers
215 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
  • 25.7k
1 vote
1 answer
70 views

How precise were the Temples' directions (East/North)

Calculating the true astronomical North/South is very simple - find the longest way and cast a shadow. Are there sources on how precise those directions in the Temples were? Are there special Jewish ...
Al Berko's user avatar
  • 25.7k
2 votes
3 answers
1k views

Biblical description of the firmament vs. round earth in the Zohar

Zohar Vaikra 10a [quotes the Book or Rabbi Hamnunab Sabah]: וּבְסִפְרָא דְּרַב הַמְנוּנָא סָבָא, פָּרִישׁ יַתִּיר, דְּהָא כָּל יִשׁוּבָא מִתְגַּלְגְּלָא בְּעִגוּלָא כַּכַּדּוּר, אִלֵּין לְתַתָּא, ...
user27343's user avatar
  • 434
4 votes
0 answers
171 views

How do the outer planets: Uranus, Neptune and Pluto fit into Judaism?

It is not a secret that we discover new things in all fields of science, not mentioned in our sources all the time. We know that in Judaism the 7 planets represent/aligned with 7 spiritual forces and ...
Al Berko's user avatar
  • 25.7k
1 vote
0 answers
75 views

Does Judaism differentiate between a planet and a star?

On the 4th day, G-d created Sun, Moon and the stars. Besides the Moon, Mercury, Venus, Mars, Jupiter, and Saturn were known since ancient times (not mentioning the existence of the real stars). ...
Al Berko's user avatar
  • 25.7k
3 votes
1 answer
215 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
  • 1,779
-6 votes
4 answers
2k views

What additional Rabbinic sources support the Flat Earth?

Rasa"G's interpretation of Sefer Hayetzirah 4,2 (c.900CE): "העולם ככפה, והגלגל אינו זז ממקומו...: (the world is like a dome and the sphere [of stars] does not move). Are there other ...
Al Berko's user avatar
  • 25.7k
4 votes
3 answers
1k views

Sources for the Earth revolving round the sun

Are there any Jewish writings that suggest the Earth revolves around the sun and is not the center of the universe?
Turk Hill's user avatar
  • 1,264
2 votes
0 answers
116 views

For the start of the day, is "sunset" astronomical or visible?

Yesterday was the equinox and I noticed that the day was longer than 12 hours according to the (secular) sunrise/sunset times. Curious, I did some investigation. One reason for the difference is how ...
Monica Cellio's user avatar
2 votes
0 answers
87 views

Keeping Two-day Shabbos in the Pacific Islands? [duplicate]

What's this I see about people in the Pacific Islands keeping two days of Shabbos? If it is true: Who, how, since when, and why?
SAH's user avatar
  • 19.6k
1 vote
1 answer
142 views

Counting and naming the stars

Why does Hashem count and name the stars in Heaven? This is mentioned in the first Rashi on Shemot, see below. I would like an explanation on this... Quote from Rashi: And these are the names of the ...
user16403's user avatar
  • 978
4 votes
4 answers
374 views

Photographing an Eclipse

There is a general prohibition on depicting and/or owning depictions of celestial bodies, such as the sun and moon (see, e.g., the Rambam Hilkhoth Avoda Zara 3:18). Nonetheless, there are opinions ...
Loewian's user avatar
  • 17.7k
9 votes
2 answers
281 views

Is there any evidence that Chazal knew what caused eclipses?

Many ancient cultures believed that eclipses are caused by things other than syzygy. The Egyptians had Apophis. The Hindus had Rahu. (The interested reader can see more here.) In light (ha) of the ...
DonielF's user avatar
  • 34.1k
0 votes
1 answer
125 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
  • 34.1k
2 votes
0 answers
38 views

The moon in the future [duplicate]

We say in Kiddush Levanah, יהי רצון מלפניך...למלאת פגימת הלבנה ולא יהיה בה שום מיעוט May it be Your will...to fill the reduction of the moon, and that there should be no diminishment in it. ...
DonielF's user avatar
  • 34.1k
6 votes
1 answer
307 views

Source for Seforno that the Earth was tilted at the time of the Flood

In Oorah's 2009 Shmorg video, one of the tracks is about Birchat Hachama, and at around the 10 minute mark, the narrator states the following (I'm paraphrasing): The Sforno writes that before the ...
user avatar
-1 votes
2 answers
233 views

Why did Hashem create only one planet (Earth) in the whole entire universe that can support intelligent life

Is there any rabbinic literature explaining why Hashem created only one planet (Earth) in the whole entire universe that can support intelligent life?
ravikumar374483593's user avatar
2 votes
2 answers
208 views

Is there lunar drift in the fixed Hebrew calendar?

It is known that there is a slight discrepancy in the average length of a year according to the Hebrew calendar and the average length of an astronomical solar year which causes a seasonal drift in ...
Daniel's user avatar
  • 24.7k
2 votes
0 answers
501 views

Shooting Stars and Luck

There seems to be a non-Jewish association of good luck with seeing a shooting star. Is there any source for this in Judaism?
Mordechai B.'s user avatar
8 votes
5 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
  • 4,576
5 votes
2 answers
404 views

Illustrated hilchot Kiddush Hachodesh

I remember seeing about 20 years ago a beautiful annotated commentary on Rambam's hilchos kiddush hachodesh, with extensive illustrations and calculations, explained according to both ancient and ...
Jeremy's user avatar
  • 8,824
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
8 votes
1 answer
359 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
3 votes
1 answer
685 views

Solar Power on Shabbos

What's the deal with using solar power on Shabbos? Cooking is permitted, but what of the following cases: 1) Heating water (Dud-Shemesh style) 2) Solar-powered watches 3) Solar-powered toys What ...
LN6595's user avatar
  • 5,310
0 votes
1 answer
402 views

What's the earliest acknowledgement of Heliocentrism in Judaism? [closed]

The English Wikipedia says that Heliocentrism was "official" in Judaism only by the 20th century: "In the 19th century, ... Hatam Sofer (d.1839) gave approbations to two books even ...
Sparkler's user avatar
  • 117
3 votes
1 answer
109 views

Are star stickers mutar?

Do any contemporary poskim discuss the usage of star stickers with regard to the prohibition of depicting celestial bodies (e.g. the glow-in-the-dark ones people put on walls and ceilings)? What if ...
Loewian's user avatar
  • 17.7k
15 votes
1 answer
768 views

We're not supposed to point at stars?

I'm an Israeli Jew living in Israel. I often give "sky tours" where I show children and adults different stars and a view through a powerful binocular at objects of interest. Recently a young boy ...
dotancohen'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
  • 40.3k
8 votes
4 answers
501 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
8 votes
3 answers
240 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
  • 17.7k
1 vote
1 answer
203 views

Where does Rashi say that Jews will be revered for knowledge of astronomy?

I remember reading a Rashi that says that the Jews will be revered for their knowledge of the stars. What's the location of this Rashi?
A Yid in Need's user avatar
-2 votes
1 answer
111 views

Does the verse in Tehillim 147:4 imply that one cannot name a star after a person?

Usually, around Mother's Day and Valentines Day, I hear a radio commercial suggesting that, as a gift to your loved one, you can name a star after him / her. (Amazing gimmick - no inventory!!) In ...
DanF's user avatar
  • 70.1k
9 votes
4 answers
325 views

Why did Hashem create the world in such a way that a leap year is needed?

I understand why we have a leap year; to keep the sun and moon cycles in sync, so that Pessach is always in the spring. That's all technical, as a result of the moon orbiting too slowly - or the sun ...
Danny Schoemann'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
  • 16k
1 vote
3 answers
1k views

What does "shachar" in "alos hashachar" mean?

We find a number of terms referring to when morning starts and then perhaps a similar term used to refer to the time of shachris. Alos HaShachar (עלות השחר) Ayeles HaShachar (אילת השחר) and Shacharis ...
Yehoshua's user avatar
  • 16k
9 votes
1 answer
805 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