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For example, in some images of the constellation Gemini, it is depicted as some sort of strange-looking elongated rectangular sunfish (see Image 1), while in others, it looks like two distinct stickmen (see Image 2). Why is this so? I figured there would be a single standardised way of joining the stars by now.

Image 1:

The constellation Gemini depicted as an enclosed rectangular shape, with the stars Castor, Pollux, Alhena and Tejat at each of its four corners. Alhena and Tejat are further joined to the stars Mekbuda and Propus respectively, forming a sort of strange-looking elongated sunfish.

Image 2:

The constellation Gemini depicted as two distinct stickmen, with the stars Castor and Pollux as each of their heads. The two stickmen's arms are joined together by the star Iota Geminorum, as if one of them is tugging the other.

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    $\begingroup$ The answer, in this particular case, is H A Rey wrote a book called "The Stars: A New Way To See Them", where he redrew many of the constellations to look more like what they are. Image 2 in your post is the diagram from his book. $\endgroup$ Commented Jun 2, 2023 at 15:30
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    $\begingroup$ See astronomy.stackexchange.com/questions/20906/… Is that a duplicate do you think? $\endgroup$
    – James K
    Commented Jun 2, 2023 at 17:25
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    $\begingroup$ I figured there would be a single standardised way of joining the stars by now. Haha! $\endgroup$
    – Michael
    Commented Jun 2, 2023 at 23:45
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    $\begingroup$ @Michael - As soon as I read that, I thought of this; imgs.xkcd.com/comics/standards.png $\endgroup$
    – Valorum
    Commented Jun 3, 2023 at 10:51
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    $\begingroup$ Is "image" the correct term here? And this seems more astrology than astronomy. $\endgroup$ Commented Jun 4, 2023 at 5:32

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You almost answer your question yourself: The answer is that there isn't a single, standardized way of joining the stars. The reason for this, from a scientific point of view, is that whatever creature some pattern of stars makes you think of bears no scientific value. We don't learn anything about the Universe by drawing these lines. They're beautiful reminders of fascinating myths, but myths have different versions and origins, so e.g. Orion can be drawn as wielding a club or a sword in his right hand, and a shield or a bear hide or a bow in his left.

That doesn't mean that the patterns are useless: To categorize astronomical objects and phenomena, it is sometimes helpful to divide the sky into regions, and one way to do this is to follow the historical constellations. For this reason, the International Astronomical Union defined, in 1928, exact boundaries between 88 constellations, following the directions along and perpendicular to the celestial equator (measured through right ascension and declination, respectively).

Bright stars are then sometimes named by a Greek letter (in general, but not always, starting with α for the brightest, β for the next-brightest, etc.), plus a three letter abbreviation of their constellation. For instance the eastern-most star in the Big Dipper, which is in Ursa Major, is called "η UMa".

However, as with most objects in astronomy, η UMa has other names as well: In the Hipparcos Catalogue it's called HIP 67301, in the Henry Draper Catalogue it's HD 120315, and when you're stargazing it's called "Alkaid". And that's good because in 62,900 years it will have crossed the border to the neighboring constellation, Canes Venatici (if you can trust Stellarium's prediction of star position beard on the proper motion). So even this practice of dividing the sky into constellations is not that helpful after all, and is of course completely arbitrary.

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    $\begingroup$ "The reason for this, from a scientific point of view, is that whatever creature some pattern of stars makes you think of bears no scientific value." Insert Ursa Minor joke here. $\endgroup$ Commented Jun 4, 2023 at 5:36
  • $\begingroup$ @Acccumulation 😄 $\endgroup$
    – pela
    Commented Jun 4, 2023 at 9:05

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