Where did TRAPPIST-1a go?

  • According to the NASA announcement and the Wikipedia article on TRAPPIST-1, the planets around the TRAPPIST-1 star are named TRAPPIST-1 b through h. What happened to "TRAPPIST-1 a"?


    As pointed out by @Adwaenyth this really is comprehensively covered in https://en.wikipedia.org/wiki/Exoplanet_naming_convention

  • ProfRob

    ProfRob Correct answer

    5 years ago

    The convention for planetary naming is that the closest planet to the star (if multiple planets are found at the same time) is named "star"b, then "star"c and so on. As correctly pointed out by Zephyr, if the discoveries are more haphazard, the order of discovery takes precedence over distance from the star).



    So, there is no Trappist-1a. Or you can think of it being the star itself if you like, although that becomes confusing if the star is itself part of a multiple star system, where it might be known as "star"A or "star"B etc. (note, capital letters), depending on where it is in the hierarchy.


    Interesting. Any idea where that convention started? I'd guess somebody somewhere called the star "star"a, and it became a convention, but I know nothing.

    Wikipedia has an article about the naming convention of exo planets including references and a few exemptions made so far.

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Content dated before 7/24/2021 11:53 AM