Some people, with good cause, do not like the phrase “dark side of the Moon”.

The reason they do not like it, is because of a common cognitive misconception.

Historically, the phrase refers to the farside of the Moon, which for most of history humanity could not observe, at all, because the Moon is synchronously rotating with the Earth and always presents the same side to the Earth.
The word “dark” here is used in the sense of “hidden” or “unseen”, which is a common colloquial use, but, in use then became confused with the more common meaning of “unlit”, leading generations of students to make the cognitive error of thinking that the farside of the Moon was “dark” in the sense of the Sun never shining on it.
Much to the irritation of Astronomers.

Some Astronomers responded to this misconception with a campaign of eradication, pushing for careful use of language, using “nearside” and “farside’ exclusively, which is all well and good, but does little to eradicate the historical usage, particularly given the strong presence of the phrase in popular culture, science errors, and all. eg Bad Astronomer’s take

So, today, when our paper on formation of the highlands on the farside came out, our press release used the phrase “dark side”.
This was quite deliberate, and we talked about the pros and cons extensively. The concept of “the dark side of the Moon” is embedded in popular culture and given the topic of the research the comparison was inevitable and best confronted head-on.

Thus: “…dates back to 1959, when the Soviet spacecraft Luna 3 transmitted the first images of the dark side of the moon back to Earth. It was called the dark side because it was unknown, not because sunlight does not reach it.”

We preferred to explicitly explain the historical context in the press release rather than ignore it.

Some people would rather we had not. They would prefer the phrase “dark side” be not used at all, and somewhat to our amusement a lengthy internet troll started about the use and abuse of the exact phrase, go google it if you must…

So, how unusual is it in this day and age to refer to ’70s concept albums?

These examples are taken over a decade+ and all taken from a popular science news website featuring articles from diverse sources discussing a range of topics, using “dark side of the Moon” to mean a couple of different things, including both the “farside” and “the part of the Moon currently not lit by the Sun”.

They are far from unique examples, and the most recent is from earlier this year.

So, it is really a matter of style and pedantry.
On the one hand, purists like to try to simplify the terminology and clean up concepts in the hope of reducing conceptual errors, on the other hand, some people try to be explicit about historical and colloquial usage and to discuss how different terms can mean different things depending on context.
There is, generally, no actual definitive authority on the issue in most such cases, and a case can be made either way. In some instances the popular cultural context is overwhelming and the science stakes are low; in other instances the scientific stakes are high and the cultural context is weak or marginal.
On this one, Roger Waters wins…

Anyway,as we all know, it is all dark.
The Moon’s albedo is very low.


  1. […] Source: The Dark Side of the Moon: a Short History [Dynamics of Cats] […]

  2. #2 speakertoanimals
    light pollution capital of human space
    June 27, 2014

    Yes, arguments CAN be made for both uses, and, as in many cases, one is just wrong! If you and your colleagues taught more intro astro, you’d know this (note: NUMBERS of students are irrelevant, huge lecture classes hardly count. ). And clearly, citing other people’s mistakes is not the best of strategies to support ones own. Having said all this, I am mightily amused that stellar astronomers and theorists MAY have solved one of the greatest problems in planetary science (and from my alma mater too!). So, kudos on the science, not so much on the “teaching moment.”

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