Friday, February 5, 2016

New Moon


I awoke to a new moon this morning. Well, it wasn't actually what some [any] astronomers would describe as a new moon. That kind of new moon would look more like the above photo. The new moon I saw is pictured below.

THE OWNER OF WEDNESDAY'S GIBBOUS MOON IS AT RIGHT IN PHOTO.

For any doubters, I used a formula I found on Wikipedia to ascertain that this was in fact a new moon. I'll paraphrase:

The length of a lunation is about 29.53 days with precise duration linked to many phenomena, such as variation between spring and neap tides. So,  d = 5.597661 + 29.5305888610 x N + (102.026 x 10^{-12}) x N-squared where N is an integer, starting with 0 for the first new moon in the year 2000, and that is incremented by 1 for each successive synodic month; and the result d is the number of days since 2000-01-01 00:00:00 reckoned in the time scale known as TT used in ephemerides. To obtain this moment expressed in UT, add the result of following approximate correction to the result d obtained above: -0.000739 - (235 x 10{-12}) x N-squared days. Periodic perturbations change the time of true conjunction from these mean values. For all new moons between 1601 and 2401, the maximum difference is 0.592 days = 14h13m in either direction. The duration of a lunation varies in this period between 29.272 and 29.833 days, −0.259d = 6h12m shorter, or +0.302d = 7h15m longer than average. This is smaller than the difference between mean and true conjunction, because during one lunation the periodic terms cannot all change to their maximum opposite value. 

NOTE (also from Wikipedia... and paraphrased):
The long-term error of the formula is approximately: 1 cy2 seconds in TT, and 11 cy2 seconds in UT.

So don't blame me if you try this formula and it doesn't work.

25 comments:

  1. I shall forever hold you blameless for anything except smiles, chocolate and hugs.

    ReplyDelete
    Replies
    1. Jacqueline:
      Thank you. (I assume you read an understood the entire formula.)

      Delete
  2. Well - you sure cleared up that issue! Actual observation trumps theory every time; the formula may need to be adjusted for your location.

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  3. We're going to a "new moon" pizza party on Monday.... Memo says that's when the women are fertile and the men are virile.... and it's the time to plant your seed. He says he's a farmer....

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    Replies
    1. Sharon:
      I'd be careful at a new moon party whose premise is to celebrate planting your seed when women are fertile and men are virile. Sounds like a bunch of "swingers" to me.

      Delete
  4. I will take your word for it, Mitch, that these are two different 'moons'. You are the expert!! lol

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    Replies
    1. Jim:
      I appreciate that vote of confidence. No formula was needed to determine that Wednesday's moon was about twice the size of Friday's.

      Delete
  5. Replies
    1. Ray:
      Would you like me to explain it again in more detail?

      Delete
  6. Something just hit my eye like a big pizza pie...but I'm pretty sure it's not amore!

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  7. Far too complicated for me to follow.

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    Replies
    1. Stephen:
      I can't believe you couldn't follow that explanation. I myself understood the first three, even four, words.

      Delete
  8. Replies
    1. anne marie:
      I just don't get it. It was a bit chilly and windy. Didn't he feel the breeze across his butt?!?

      Delete
  9. I use that formula all the time. It works. Trust me. But you have to be careful of those neap tides. They'll trip you up every time.

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    Replies
    1. Walt the Fourth:
      That's exactly where I usually get confused.

      Delete
  10. Looks like you were up at the crack of dawn. Again.

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    Replies
    1. The Cranky:
      I love it. That could be the blog title next time!

      Delete
  11. I am so confused with all those numbers ~ but you know what that moon is over here too!!

    Invasion of the Moon People!

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    Replies
    1. Ron:
      I don't know how such a simple formula could confuse you. Have Sophie explain it.

      Delete
  12. I am a Cancer, a moon child. The coming and going of the moon is paramount to our moods.

    ReplyDelete

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