Related: https://physics.meta.stackexchange.com/questions/4223

We tried an astronomy Stack Exchange site, and it ended up being merged with Physics after the beta ended unsuccessfully due to lack of traffic. What makes us think this proposal wouldn't have a similar fate? What has changed since last time?

Proposal: Astronomy & Astrophysics

  • 4
    Looking at the world, astronomy and physics co-exist as two separate disciplines, and both thrive. I think there's enough space for two separate sites. As for change (or what needs to be changed), I go with Jeremy Taylor's response below.
    – 9769953
    Commented Jan 21, 2013 at 14:59
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    @Evert The are most certainly not that separate, any more than particle physics is separate from quantum mechanics. They do not thrive independently. No professional astronomer ever lacked a solid background in general physics. And huge branches of physics (nuclear reactions, neutrinos, general relativity, even Newtonian mechanics) would probably not exist at all if not for astronomy.
    – user71091
    Commented Apr 24, 2013 at 0:00
  • @Chris I never said they were separate and independent, just that they exist as separate disciplines. They both thrive; never said independently. It would appear that there is enough scope for both of them to exist actively. After all, there is Chemistry, which may or may not have large overlaps with Physics.
    – 9769953
    Commented Apr 24, 2013 at 14:01
  • 1
    @Evert: I believe this depends on the university, country, and culture. At our university, the institute of astronomy and astrophysics is a regular part of the faculty of physics, just like the institutes for material physics, particle physics, etc.. That doesn't mean much for this proposal, though.
    – jdm
    Commented Apr 25, 2013 at 6:48
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    @Evert, Dear friend, since Newton's Principa, astronomy has never co-existed as a separate discipline from physics. It is so. Moreover, Astronomy has been and today still is the motivation and raison d'être for the many of the most important physics advances, and certainly for almost all of them until the 1930s. It is not a question of simply overlapping, but a deep essence. I understand that some people have bad memories from school times and hate to see an equation. There are other sites for them already in internet. Astronomy questions fit naturally well in the existing Physics site.
    – user85401
    Commented Apr 26, 2013 at 16:24
  • 2
    As someone who was relatively active on the old astronomy.SE shortly before its death the majority of questions on it were popsci level astrophysics. Observational astronomy and astro-photography were a small minority of the total questions. I don't think adding Astrophysics to the title of this proposal will help since the main problem was a failure to bring in large scale participation from the observational astronomy community from elsewhere. Commented Apr 30, 2013 at 20:15
  • Similar question at the new site's meta area: How is the current Astronomy compared with the old one? Commented Nov 5, 2013 at 1:15

6 Answers 6


Just a note: After Astro.SE was merged into Physics, we included Astronomy into our scope (astrophysics already was there). So this proposal is a proper subset of Physics.SE.

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    I agree. All the questions I see on the definition page would be welcome on Physics.SE and many (most?) have already been asked and answered there. Some have been asked and answered on both physics.se and astro.se (before the closure and merger). Not that I oppose this proposal, but I'm not sure what exactly would be gained by it. Commented Dec 1, 2012 at 5:04

I, as an astrophysicist (and amateur astronomer as well), feel that creating this site is not a good idea at all. There is already an excellent Stack Exchange site where all astronomer and astrophysicist questions fit very well, here and have better chances to be answered because astrophysics overlaps with many (if not all) fields of physics.

A separate site for astronomy would only fragment the audience of your question, therefore creating a separate astronomy site would lower the probability of getting a good answer to your question. Part of the beauty of astrophysics is that it combines many branches from different fields.

Do you have a question about black holes? Then you want your question to be read mainly by theoretical physicists, not only by astronomers.

Are you wondering about the cosmic background radiation? Particle physicists are likely to give you the answer.

You may have a question about telescopes. What makes you think that a microscope physicist or someone doing his PhD in physical optics will not give you the best answer?

I could go on, because, as I said above, astrophysics combines many branches. Please avoid fragmentation and have a look at the fantastic site we already have. If you are in any case interested only in directly-related astronomy questions, you can easily filter questions, for instance thanks to these tags that already exist in the physics site:

  • Astronomy
  • Observational astronomy
  • Astrophotograpy
  • Astrophysics
  • Astrometrics

Questions related to amateur astronomer observing are welcome too, see for instance "Issues with Celestron 130 SLT and shaking". Please don't lower the chances of getting a good answer to your question. Don't support the creation of this site.


Who ever set up this proposal is probably unaware of the slow death of the previous Astronomy Q&A proposal.

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    It could very well be that people were aware: this proposal might be considered a variation of the previous proposal, with a slightly extended scope.
    – 9769953
    Commented Jan 21, 2013 at 14:56

The team supposedly reviews proposals when they reach about 45% commitment to make sure they really are appropriate and aren't duplicates. If that's true, they probably should have looked at this one in more depth. The statistics and the opinion of the majority of the experts support a single site for Astronomy rather than two.

Assuming cosmology is on-topic here (based on this), there are 3 large tags (>200 questions) on Physics SE which would be included, namely [astronomy], [astrophysics], and [cosmology]. Between those three, there are 1388 questions. I am ignoring [general-relativity] and [black-holes] because in my experience the experts on these subjects are more commonly described as physicists than astronomers, but if those are included it bumps the level up to 2579 questions. There are other smaller tags as well such as [observational-astronomy], but let's only consider these big three for now, since they are enough to prove my point. Between them, thir 1388 questions is roughly 7% of all questions on the site. Equivalently, that's roughly 3 questions per day, which is already more than many (roughly 30) of the smaller sites on the network. There is already a thriving community of astronomy experts on Physics SE.

For comparison, if we scaled Physics SE up to Stack Overflow, that would correspond to [android] breaking off and making their own site for Android developers. Equivalently, it would also correspond to roughly 1.4 times the size of [python], a site which was proposed and subsequently closed on Area51 as a duplicate of SO at least once. I'm pretty sure a Python site or an Android developers site is never going to happen, because it's a terrible idea, but that's what would happen here to Physics SE if this site were created. Or we could compare to GitHub. While the tag for GitHub on SO has only about 0.1% of all the questions, the GitHub proposal was closed as a duplicate of SO. Astronomy and Astrophysics are 70 times more important to Physics.SE than GitHub is to SO. Also, keep in mind that the Physics SE community is much smaller than that of SO. On Physics SE, the community and the site is small enough to the point that losing 7% of the questions would be a very significant problem in terms of the prolonged longevity of the site, while on SO it would be barely noticeable. Splitting Astronomy between two sites would have a significant adverse effect on the existing Physics SE community.

Let's look at the existing [astronomy], [astrophysics], and [cosmology] questions on Physics SE in more detail. Of the 1388 questions, 94 are unanswered. That's nearly a 93% answer rate, 5% better than the overall answer rate at Physics SE. It's probably reasonable to expect that cosmology will be less popular than the other two on a site called Astronomy & Astrophysics. If we only consider [astronomy] and [astrophysics], there are 839 questions, of which only 43 are unanswered. That's over a 95% answer rate. By all standards, that's an excellent answer rate. So it's not like the astronomy questions are going unanswered on Physics SE.

Skeptics might claim that this doesn't imply that they're being answered well, but the evidence seems to suggest that they are high quality and highly valued contributions. This query (run on June 12th, but the results haven't changed a lot) shows that among tags with at least 1000 answers, [astronomy] has the highest average answer score. [astronomy]'s 4.02 average votes per answer is significantly higher than [mathematical-physics] at 3.28, [soft-question] at 3.22, and [particle-physics] at 3.15. No other tags are above 3. Going down to tags with 500 questions with this query, the only tag with higher score than [astronomy] is [research-level] which is mostly kept around for historical reasons since it was added to all questions from the closed Theoretical Physics beta site. [astrophysics] comes in at #5 on this tally with 3.29 average votes (above [mathematical-physics]), while [cosmology] is right around the average site-wide. That isn't what I'd expect if astronomy and astrophysics were lowly valued on the site; rather it's indicative that astronomy/astrophysics answers are considered high quality and interesting by many of the existing Physics SE users.

The evidence is that astronomy and astrophysics questions are getting asked in large amounts and answered well on Physics.SE. The people supporting this proposal might claim that the questions on Physics.SE are not representative of the types of questions which they want to ask, and that they would be focusing on more specialized astronomy questions which would not get good answers without being on a specialized site. So let's look at their definition questions. The situation is exactly the opposite of this. The majority are pop-science level questions. They aren't questions that would require an expert in astronomy to answer (for my purposes, an expert is someone at least at the graduate level in terms of knowledge, e.g. the "Expert" and "Academic" categories). Many of these questions could be answered by a simple Google search or by reading the relevant Wikipedia article. There are a few reasonably advanced questions, but nothing so advanced that they probably wouldn't get answered on Physics SE (and, in fact, many of the questions have already been asked on Physics SE). I'm certainly not an expert in astronomy, but I found I immediately knew the answer to 31 of the 40 example questions with only basic high-school level material. I think everyone will agree that, looking at Physics SE's list of recent questions right now, the majority of the questions are at least at the level of an introductory college course in physics. So in a sense it is true that their questions would be atypical for Physics SE, in that they'd be disproportionately bottom-of-the-barrel stuff. However, they're not anywhere near off-topic, and they'd still probably get answers so long as they're asked well and at least slightly less trivial to answer than linking to Wikipedia. This site will not help anyone get an answer to their astronomy questions who couldn't already get it on Physics SE.

The fact that this site is likely to be populated by pop science rather than real science is further evidenced by looking at exactly who has committed. Of the 151 current commitments, only 37 (22%) were self-described as either "Expert" or "Academic or Research-level student". The remaining 78% of the commitments come from people who are at best enthusiastic about the subject, and in many cases just curious. That isn't a very good mix. For contrast, the Biology proposal had 61% in the two Expert categories and Chemistry had 51% (Physics entered beta before committer roles existed). Judging by avid user counts, Chemistry is still arguably having problems with their lack of experts, and this site would have less than half as many self-proclaimed experts. This might not damning evidence by itself, but at the very least it's worrying that the experts (including those already on Physics SE) aren't committing to this proposal. It's very likely that it will only fragment the existing astronomy and astrophysics communities on Physics SE rather than creating a new expert community even if it does succeed. At the moment it doesn't even seem to be creating an expert community at all.

The fact of the matter is that it's at least as common for Astronomy and Physics to be in the same department as separate in Universities. That is to say, at the expert level (which is the level at which SE communities are built), astronomy isn't really separate from the existing physics community any more than geophysics or plasma physics is (two areas which also are sometimes separate and sometimes integrated into physics departments). I assume if I were to propose a site for Plasma Physics, it would be quickly identified as a duplicate, and this case is really no different. In academic culture, astronomy is already fairly well integrated into physics, and since the experts are academics, that's the culture we should care about. The fact that amateurs see these as more disjoint than they really are should not factor into the equation at all.

With all of this, I can not find anyone on Physics.SE who thinks this proposal is a good idea and has a strong reason why. Most people think it is a terrible idea, as evidenced by this thread. That includes professional astronomers and astrophysicists, the very experts who are targeted by this proposal. I was only able to find 7 committers to this proposal who have at least 500 rep on Physics SE. That strongly suggests that the majority of the people here just don't want to participate in Physics SE for whatever reason. I do not know why they are unsatisfied with Physics SE, but unless they voice a reason there I also do not think it is important why. We've already established that there's a sizable number of people on Physics SE who are doing astrophysics; the inability of this proposal to attract many of them speaks volumes.

While I think I've written too much already, it's worth going over the checklist from the "Should my idea be part of an existing site, or its own site?" section of the FAQ one more time to see what SE's official decision should have been:

In general, if a site makes sense as part of a bigger site, it's better to have one big site than a bunch of little niche sites. Site X should be subsumed by site Y if:

  1. Almost all X questions are on-topic for site Y
  2. If Y already exists, it already has a tag for X, and nobody is complaining
  3. You're not creating such a big group that you don't have enough experts to answer all possible questions
  4. There's a high probability that users of site Y would enjoy seeing the occasional question about X
  1. Yes, all questions here would be on topic on Physics SE. There is no debate on this point.
  2. Yes, several tags already exist, are getting good answers, and none of the experts on Physics SE are complaining about this. The people who are complaining don't even participate on the Physics site and don't have a good reason why.
  3. Yes, this proposal has a dearth of experts. The experts are already on Physics SE and don't want to split. The people who want a new site are almost exclusively novices who could get their answers on Physics SE, Wikipedia, Google, Yahoo! Answers, or pretty much anywhere else.
  4. Yes, there is interest in Astronomy on Physics SE. The answers in [astronomy] and [astrophysics] tend to generate significantly more votes than average, signifying strong community interest.

On all four counts, Physics SE should subsume this proposal. This is exactly the sort of case which closing as duplicates is supposed to cover (according to the blog posts Merging Season and An Area 51 Apology — and Clarification). My only guess as for why it wasn't closed is that the team lacks anyone knowledgeable about the culture of physics and the Physics site, and thought this might be worth a try. It's not worth a try, any more than a Python-specific or Java-specific site is worth a try. There are only two possible outcomes. Either the site will fail, in which case it will get folded back into Physics SE (but not without hurt feelings and a lot of work on the part of everyone involved), or it will succeed and divide the community, creating a new site filled mostly with pop-science and few experts, benefiting precisely nobody.

  • 1
    I participated in the old Astro.SE, and I don't see why another try would work. That said, how many of the questions in your statistics were asked before Astro.SE was subsumed into Physics.SE? My personal feeling is that there are fewer astro-related questions on Physics.SE than there were new questions on Astro.SE before the merge. But that's totally unsubstantiated by numbers, so I'd be interested to be corrected.
    – Warrick
    Commented Aug 11, 2013 at 17:43
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    @Warrick I didn't look into that, so you're right that the statistics could be invalidated. It's hard to control for which questions are from the astronomy beta and which aren't. Questions migrated from closed beta sites don't have any indication of this. One could probably write a custom data.SE query to exclude all questions from this time period of the previous Astro beta, but I'm not familiar with SQL so I'm not able to...
    – Logan M
    Commented Aug 11, 2013 at 23:37
  • 1
    (...) The recent statistics over the past few weeks seem consistent with the numbers I've given of about 3 Q/D in all astro-related tags (when Astro SE closed it was at 1 Q/D). I don't know how many questions Astro SE had when it was closed, so that's the best I can do with the limited statistics I have.
    – Logan M
    Commented Aug 11, 2013 at 23:37

Well, I never supported the last one because I never came across it! It needs to be publicised in order to get support.

  • 1
    While I'd like to have such a site, my concern is that while we may attack new supporters, it is likely we would lose old ones. I'd anticipate that the support level overall would be unchanged from last time, which while not terrible, was not sufficient to ever get out of beta.
    – WilliamKF
    Commented Oct 30, 2012 at 20:32
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    Attack new supporters? Why? Commented Oct 31, 2012 at 4:58
  • Nor do I understand your reasoning about losing old supporters. Why not give it a solid crack, and see where the cards fall? Commented Oct 31, 2012 at 4:59
  • It is possible the old supporters have moved on to other interests. Unless something is done significantly differently than last time, I see no reason to expect substantially different overall participation. Its not just supporters you need, but involvement of sufficient numbers to create a thriving community.
    – WilliamKF
    Commented Oct 31, 2012 at 13:25
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    s/attack/attract/? Commented Dec 1, 2012 at 5:07
  • Above I had a typo where I wrote attack where I really meant attract as correctly surmised by @dmckee above.
    – WilliamKF
    Commented Jan 19, 2013 at 0:14

A separate SE for A&A would attract more people to the site, as professionals and enthusiasts. Astronomy is much more popular than Physics, among laymen. A specific site will help users to get more focussed questions and more focussed answers.

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    But we had a specific one and it was merged into Physics due to lack of traffic I suspect. How would this new proposal not have the same fate?
    – WilliamKF
    Commented Sep 7, 2012 at 14:39
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    It will if people have a negative attitude. Why not ask: How can we promote this so that it doesn't suffer the same fate as the Astronomy proposal? Commented Oct 30, 2012 at 3:57
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    Merging sites to where they belong is not necesarily having a negative attitude. See this blog post about it. Commented Dec 5, 2012 at 16:11
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    Use the "Astronomy" and "Observational Astronomy" tags in the Physics site, that's all. Nothing else is needed...
    – user85401
    Commented Apr 23, 2013 at 23:20
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    For questions on topic in both, what group of people could you attract to this proposed site that would be scared away from physics.SE, especially given the ability to filter tags? The answers may very well be different, but will they be better here?
    – user71091
    Commented Apr 23, 2013 at 23:50

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