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 defines "on this earth" as it relates to the halachic necessity of performing mitzvot?

Presumably the earth's atmosphere would count as "earth," but why? You are not literally "on [the] earth" when you are in the atmosphere.

And what about Space outside the atmosphere? Do the Commandments not apply there?

From a logical standpoint, it seems absurd that one might be allowed to murder or worship idols while aboard an airplane, or a rocket ship, for that matter. But does halacha itself account for these situations in any reliable way?

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    One perspective mentioned in the answer I linked above is that of Rabbi Shlomo Goren, who reasoned that (according to the answer): "since one cannot survive in the environment of space without bringing earthly oxygen and water with him, he is still 'on this earth' for purposes of this, now, very real discussion."
    – SAH
    Mar 13, 2013 at 18:31
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    I wonder if this can be interpreted along the lines of Ramban's position that Eretz Yisrael, in particular, is the primary place for observing all mitzvot. Perhaps that's what "on the earth" means here, too?
    – Isaac Moses
    Mar 13, 2013 at 18:36
  • I remember seeing that Rav Menashe Klein held if one was on the moon itself he would say kiddush levana.
    – sam
    Mar 13, 2013 at 18:39
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    What about shooting someone while jumping? Mar 13, 2013 at 19:37
  • 4
    What about לא בשמים היא! Jul 21, 2014 at 17:53

1 Answer 1


I could theorize that according to R. Firrer, the 'halakhic Earth' would be defined as anywhere that one is still subject to the Earth's gravitational field. Actually reading the article, however, implies that either 1. as soon as something is not touching Earth, it is no longer governed by its halachos (which, as you point out, is ridiculous) or 2. anything that has left Earth would still be Earth-bound material until it touches the moon, at which point "halakhic Earth" status gives way to "halakhic moon" status (maybe you could make kiddush levana upon seeing a person who walked on the moon, until he walks upon Earth...)

Honestly, though, R. Firrer's opinion is quoted by R. J. David Bliech as being 'extreme', and I'm sure that no posek would agree to his "radical point of view", including R. Goren, who R. Firrer quotes as saying that time bound commandments are not applicable outside of earth, where there is no measurable time.

That being said, regarding serious discussion of the "halakhic Earth" (or "hashkafic Earth"), both R. Soloveitchik and R. Yaakov Kamenetsky (Emes L'Yaakov Beraishis 1:1, 5761 edition) have been reported as saying that it includes any reachable part of the physical universe. R. Schachter tells the story that some students came to R. Soloveitchik who were very bothered by the fact that someone could leave Earth and touch the moon, due to the pasuk השמים שמים לה' והארץ נתן לבני אדם - the Heavens belong to Hashem. As this story is quoted in Beis Yitzchak 5754 (translated here), R. Soloveitchik responded

The term "heavens" can be explained in two ways — as something high and/or distant, as it says "It is not in the heavens" (Deut. 30:12), according to which the moon is considered a part of the "heavens." Alternatively, the term can be defined as including everything that is beyond human understanding, including the entire spiritual realm. According to this second understanding, the stars and most distant galaxies — and certainly the moon — are considered part of "earth." Therefore, [according to this latter interpretation,] there is no contradiction between traveling in space or scientific studies of the cosmos and the verse "The heavens are for the Lord and the land for mankind."

The way that I heard this story from R. Schachter, he connected it to the words of the Ramban on the first pasuk of the Torah, who says that "שמים" in the Torah refers to heavenly beings, but anything that is physical, including everything that is discussed in detail in the first chapter of Beraishis, is included in ארץ. This is what R. Kamenetsky is said to have believed as well:

We learn from these words of the Ramban [on Gen. 1:1], and in particular from what he concluded in the continuation of his words on verse 8, that everything that exists in the creation in the entire world, including the sun, the moon and all the heavenly hosts, are not called "heavens." The "heavens" are only things that have no physical bodies, such as angels, hayos and the merkavah. However, anything that has a physical body is included in the name "earth" in verse 1 (translated here too)

  • See also R. Soloveitchik's Chamesh Derashos, p. 92: אין קדושת ישראל נפקעת אף אם יהודי נמצא על הירח!
    – wfb
    Nov 3, 2016 at 20:29
  • @wfb why would anyone think otherwise? Nov 15, 2016 at 18:06
  • he seems to be rejecting the view of r. fierer. a jew is always obligated in mitzvot
    – wfb
    Nov 15, 2016 at 19:38
  • According to the scientific consensus, the Earth's (and for that matter any mass') gravitational field extends into infinity and does not stop.
    – user17319
    Sep 10, 2021 at 2:40
  • @Tesvov while that may be technically true, increasing the distance from Earth reduces its force exponentially (since gravitational force obeys an inverse-square law), and at a certain point the force is negligible, and halacha only takes into account discernable forces. Although maybe you're right to question the idea in this respect: what if you are orbiting the Earth, and thus subject to its gravitational pull, but not perceptibly being pulled towards it? Sep 12, 2021 at 19:24

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