The first commandment of the Torah is to be fruitful, multiply, and fill the earth/land (הָאָ֖רֶץ).

The question is whether Mars (and other terrestrial planets and moons) should be included in the definition of הָאָ֖רֶץ.

  • 2
    Is there a mikvah there? Do they have bagels? And a daf yomi shiur?
    – pcoz
    Sep 10, 2021 at 5:14
  • I think you should ask whether we're commanded to colonize Earth first. I didn't hear about it.
    – Al Berko
    Sep 11, 2021 at 17:59
  • "in the beginning G-d created the Heavens and the Earth" - mars is in heaven. furthermore are we commanded to colonize antarctica?
    – user813801
    Oct 13, 2021 at 18:08

3 Answers 3


G-d did not command man to fill any specific geographic area, so colonizing additional area (on earth or elsewhere) does not directly fulfil any commandment.

Ramban explains "fill the earth" (וּמִלְא֥וּ אֶת־הָאָ֖רֶץ) as G-d's blessing to mankind to increase in numbers and populate vast areas; and "and subdue it" (וְכִבְשֻׁ֑הָ) as G-d's gifting mankind the power to dominate the rest of His creation.

  • Hmm, in that case "be fruitful", "multiply", and "fill the earth" all seem redundant.
    – Doug
    Sep 10, 2021 at 4:25
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    "Be fruitful and multiply" is a commandment to have children. "Fill the earth" is a blessing which gave mankind the ability to populate vast areas.
    – user17319
    Sep 10, 2021 at 5:10
  • Why does not the plain meaning govern when that is clear and, by all means, plausible? Oct 10, 2021 at 5:09
  • @AndrasEmet - the above explanation of Ramban represents the plain meaning of the words in this passuk.
    – user17319
    Oct 11, 2021 at 2:52
  • @Tesvov can you how reading the commandment-blessing distinction is read into the text? It appears hard for me to see it the plain meaning of it. Maybe the context would support your reading it being the plain reading of it, but then again: If you need context, that is, by definition, not the plain meaning. Oct 11, 2021 at 3:35

This may be a simple answer, but celestial objects are never referred to as הָאָ֖רֶץ in Tanach. The word is only used in reference to the Earth that we live on.


Welcome to Mi Yodeya and thank you for sharing your fascinating question, Doug! Rav Moshe Heinemann says in the name of his Rosh Yeshiva, Rav Aharon Kotler zt"l, that we are not supposed to travel outside of earth based on the verse in Tehillim (115:16):

הַשָּׁמַיִם שָׁמַיִם לַה' וְהָאָרֶץ נָתַן לִבְנֵי־אָדָם׃ The heavens belong to the LORD, but the earth He gave over to man.

Hashem gave this earth to us to inhabit, but outer space is His. Accordingly, it is a commandment for us to inhabit THE earth, the only one we are allowed to inhabit.

  • 2
    Can we fly in airplanes?
    – Double AA
    Sep 10, 2021 at 0:36
  • @DoubleAA The issue is seemingly to break beyond the gravitational pull of earth, hence the issue of the dor haflaga's spaceship. Airplanes fly in the lower orbit where they must still fight gravity.
    – NJM
    Sep 10, 2021 at 1:04
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    See judaism.stackexchange.com/a/43683/13811
    – NJM
    Sep 10, 2021 at 1:06
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    Does he say that as psak, or was it just a general hashkafic statement?
    – Yehuda
    Sep 10, 2021 at 1:44
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    @NJM even in high orbit there is the pull of gravity. Weightlessness in space as you've seen it is more technically an illusion because the ship is constantly falling. It's not because gravity is weaker up there; that's a common misconception
    – Double AA
    Sep 10, 2021 at 2:04

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