If you see a large enough river, you say עושה מעשה בראשית. This is only if the river is as it was originally created and its path has not been changed by human activity (OC 228:1-2).

If you see a comet or asteroid, you also say עושה מעשה בראשית (OC 227:1). Can you say this bracha on an asteroid that has had its path changed by a human mission?

(This question was inspired by DART but is not so relevant to Dimorphos, because if you see it you'd also see Didymos, and Didymos's path has not appreciably changed. It might be more relevant to Tempel 1, especially according to the Eliyah Rabbah cited by MB 228:5, and to targets of future missions.)

  • Do the rules of "changed course" apply to any other natural phenomenon?
    – Double AA
    Nov 25, 2022 at 15:20
  • @DoubleAA That's my question. Nobody until recently would have imagined that this was a possibility so they wouldn't have mentioned it for anything other than rivers and seas even if it's a general rule.
    – Heshy
    Nov 25, 2022 at 15:32
  • What about lightning hitting a lightning rod?
    – shmosel
    Nov 28, 2022 at 3:59

1 Answer 1


It's a good question. Yalkut Yosef says in Brachot 228:16

Contemporary Poskim debated whether the blessing of ose ma'ase bereshit is to be recited over other natural phenomena that inspire wonder and awe, such as volcanic eruptions, caverns of stalactites and stalagmites, natural geysers and waterfalls. In practice, we must apply the principle of safek berakhot lehakel and recite the blessing without pronouncing God's Name.

The footnote:

The Or Letziyon (Vol. II, 46:62) ruled that this blessing is to be recited upon entering a cavern filled with stalagmites and stalactites...Obviously, he was certain that these features have existed since the world's creation... According to the Or Letziyon the list of phenomena in the Mishna - thunder, lightning, shooting stars etc. are only examples of natural awe-inspiring phenomena... Harav Hayim Kanyevski ruled that the blessing can be recited over those phenomena listed in the Mishna only. The Halakha Berura (page 481) concurred with this.

Regarding Rivers, the footnote for (ibid) 9:

Regarding the Tigris and Euphrates rivers, the Mishna Berura (228:5) cited the Eliya Rabba rule that if one has reason to suspect that the section of the river he is viewing was diverted at some time, he must not recite the blessing. In the Sha'ar Hatziyun he cited the Peri Megadim who ruled that unless one knows otherwise, one may assume that it was not diverted, but he added that he is reluctant to rely on that. We must apply the principle of safek berakhot lehakel. This matter needs more research.

As you can see, the most contemporary poskim have not thoroughly investigated even the matter of rivers.

The principle does seem to be the same between rivers and all other natural phenomena this bracha is stated on - it is to do with whether they have existed since creation. The question becomes, does a "diverted shooting star" fall into the "diverted river" camp?

On the one hand, a shooting star that would have been seen before it is diverted, can be considered as still something that has "existed since creation", but on the other, one can make this argument about diverted rivers as well. All we have done is divert it, but it's not like we made the river. Still, the diversion removes it from its status as "existing since creation" and we no longer say a bracha on it.

So we should certainly not feel qualified to give an answer here on Mi Yodeyah, and leave it to the gadolei adar to do "more research" and get back to us on the matter.

In the meantime, it seems safek berakhot lehakel is a very strong principle when there's even the slightest doubt (and it seems there's a strong reason to doubt here) as the Yalkut Yosef does with these "other natural phenomena" even though he is very pro-saying shem u'malchut for the "special brachot" in general (see ibid 224, 226-229), so certainly in this case, until the gadolim do the research, I wouldn't say a bracha with shem u'malchut on a diverted comet.

Remember, Mi Yodeya answers are never intended to be taken as psak.

  • R' Ovadya and R' Chaim don't apply safek berakhot to shooting stars. They apply it to other natural phenomena that aren't in the mishnah's list. This one is in the explicit list.
    – Heshy
    Nov 25, 2022 at 15:30
  • @Heshy you are right, apologies. I have made an edit. I may still be misunderstanding Yalkut Yosef. Let me know what you think.
    – Rabbi Kaii
    Nov 25, 2022 at 15:37
  • "When it comes to other natural phenomena, even when it comes to standard, undiverted shooting stars, Yalkut Yosef is uncertain enough that we say we safek berakhot lehakel!" where does he say that?
    – Heshy
    Nov 25, 2022 at 15:42
  • After mentioning the opinions we can say it for those listed in the mishnayot, he immediately says "In practice, we must apply the principle of safek berakhot lehakel, as stated above". I find this unclear, but I took it to mean "still, we don't" @Heshy. I am turning off my PC now for candle lighting, shabbat shalom
    – Rabbi Kaii
    Nov 25, 2022 at 15:44
  • 1
    That's after he mentions the opinions we can say it for those not mentioned in the mishnayot.
    – Heshy
    Nov 25, 2022 at 15:46

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