The standard for is that we should edit out the tag if hard science is obviously not wanted. I.e. the asker doesn't want to require equations or citations in the answers.

In this question, the asker wants to know how to calculate the distance. One calculates distances through mathematical equations. In this case, the equation is called the law of cosines and is a more general form of the Pythagorean theorem.

The tag was removed with an edit reason of

Removed hard-science tag, because this is in essence an elementary math problem with one definite answer, so it is not appropriate to ask for evidence.

Is that correct?


6 Answers 6


, and tags specify the perspective the OP wants on the answers.

As such, editing out or in those tags is something that solely the OP can do. Any other user doing it is just messing around with someone's else post. Nothing prevent to leave a comment asking the OP to reconsider the tag usage, but again, it's up to the OP, and OP only, to change those tags.

On a side note, I think you did the right thing by rolling back the edit.

That the question was an elementary trigonometry problem has nothing to do with the tag to be used.



The tag should not have been removed and I reverted the previous change. My edit reason

Hard science asks for equations or citations. In this case, it can be answered with equations.

I will regard up-votes on this answer as votes for retaining the tag and down-votes as votes that this is not the reason. If you think that this was the correct decision but the wrong reason, please post your own answer (or vote up an existing one if already created). And if you disagree with the decision, either post your own answer or up-vote an existing one.

  • $\begingroup$ The question basically asks for the formula of computing the angle between two stars knowing their coordinates (declension and right ascension). This formula $\theta = \arccos (\sin \delta_1 \sin \delta_2 + \cos \delta_1 \cos \delta_2 \cos (\alpha_1 - \alpha_2))$ must have appeared in thousands and thousands of books of trigonometry and practical astronomy published in the last four centuries, not to mention in the most cursory Google search. $\endgroup$
    – AlexP
    Commented Jun 9, 2019 at 20:01
  • 5
    $\begingroup$ @AlexP So post that as an answer so we can vote on it. I would note though that "not enough research" is not a reason not to use the hard science tag. It might be a reason to down-vote the question. Although I would point out that most people won't know how to find the delta and alpha values for a given star. Yes, this is basic astronomy. But this is a site for people who are not even basic astronomers but want to write consistent values. $\endgroup$
    – Brythan
    Commented Jun 9, 2019 at 20:08
  • $\begingroup$ Additionally I think we also need to consider the fact that the tag attracts the attention of people who might know the actual equations if they follow that tag. $\endgroup$
    – Mathaddict
    Commented Jun 19, 2019 at 20:17

It was and is irrelevant

The user is asking for the procedure / equation to calculate the distance between two stars while first knowing their locations relative to Earth. The only way to answer the question is by providing that equation and teaching that knowledge — an answer that meets the mandate. Therefore, it was (and is) irrelevant whether the tag is used.

For the record, the title to your post ("Is spatial trigonometry hard science?") is click-bait. That doesn't match the question in the body of your text, which is, "was the removal of the tag appropriate in this case?" Tsk-tsk.



The question would seem to observe that there is a distinction between information (in the sense of gathered and pre-analysed data) and mathematical logic. I concur.

My illustration:

However, as myself and a good proportion of the community here finished the eighth grade without failing to pick-up on that particular point of mathematics, the term (the sort of thing one is used to dealing with at degree level or later) would seem condescending to those who perhaps had more "cool" things to do than pay attention in class and study Pythagoras' theorem - one of the most basic tenets of world mathematics.

Would If we are asked: * "What if a world is split in half - then how many worlds would there be? Because I don't know " be a valid question?.

The issue would seem to be: Should we downgrade the quality of the requirements for the tag?



The fact that the science is easy doesn't detract from its "hardness". Nor does the fact that it may be off topic.

Requires answers backed up by equations, empirical evidence, scientific papers, other citations, etc. Contrast with: science-based and reality-check tags. This tag should never be the only tag on a question because this tag frames how a question should be answered, not the topic. Review the tag info before using this tag, and flag your question for moderator attention once posted to have the hard-science notice added.

It's not a hard question to back up with equations, whether it's off topic doesn't detract from the fact that a hard-science answer is fundamentally what you should be giving for a question like that.



In this instance!

The tag exists so that queries requiring number crunching in order to answer receive sufficiently adequate mathematical & scientific support.

Requires answers backed up by equations, empirical evidence, scientific papers, other citations, etc.

The query in question is a simple "how-to" question. It belongs either in Astronomy or Mathematics, not Worldbuilding. In so far as it remains in Worldbuilding, answers definitely do not require equations or citations in the way hard science queries require them. It requires nothing more than an explanation as to how astronomers measure the distance between stars.

Removing the hard science tag was entirely appropriate.


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