• 10_0@lemmy.ml
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    12 hours ago

    See how did sharks swim north without the north being there?

  • falsemirror@beehaw.org
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    16 hours ago

    Unfortunately (or fortunately?) this appears to be untrue.

    Polaris is a cluster of stars formed about 2 billion years ago. Sharks originated about 450 million years ago.

    One star of Polaris (Aa) appears to be 50 million years old, but it seems likely due to a collision of stars which added mass to it.

  • essteeyou@lemmy.world
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    20 hours ago

    Polaris is 45-67 million years old.

    The oldest total-group chondrichthyans, known as acanthodians or “spiny sharks”, appeared during the Early Silurian, around 439 million years ago.

    It’s not even close.

    • toynbee@lemmy.world
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      13 hours ago

      I came here to question whether that claim is true, saw your post, and thought something like “well, that settles that.” Then I scrolled down and saw neatchee’s (great username) post and now my whole world is uncertain.

        • mkwt@lemmy.world
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          17 hours ago

          Polaris goes in and out of North Star status on the 26,000 year precession cycle. So for the duration of humanity (let’s say 100,000 years), there have been decent chunks of time where it’s not in use.

        • ZeffSyde@lemmy.world
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          9 hours ago

          Eh, they got to see the thousands of other stars that are now obscured by light/atmospheric pollution.

  • neatchee@lemmy.world
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    20 hours ago

    This is only sort of true, unfortunately. Polaris is a two-star system: Polaris Aa and Polaris B.

    Polaris B is much older than sharks, by several billion years.

    Polaris Aa appears to be younger than sharks, at a measley 50 million years old, compared to sharks’ 420 million years

    HOWEVER it is unclear whether Polaris Aa is actually that young. Scientists believe that, based on some contradictory findings, that measurement may be inaccurate if Polaris Aa is formed from two different stars that merged. In that scenario, the model we use to calculate star age would no longer work and could give wildly inaccurate estimates of the star’s true age

    TMYK

    • davidgro@lemmy.world
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      1 hour ago

      In my opinion Polaris B and Polaris Ab (it’s actually a three star system!) don’t count as ‘The North Star’ because they contribute almost nothing to the visible light seen without a telescope. Without Aa there’s just no north pole star at the moment.

      But that’s interesting about the age being uncertain. I’d use the age of the merger as the age of the star anyway unless it didn’t add much mass (but in that case it would have been a short lived giant anyway…) which would still likely put it under the 420 million years mark.