The flyby anomaly is an occasional, unpredictable, and as yet unexplained discrepancy in acceleration of satellites when they pass close by the Earth. It causes an increase of up to 13 mm/s during flybys but we have no understanding of it and how to predict it.

The laws of centripetal force predict that due to rotation, the more dense molten material within the Earth might accumulate at the equator, since there it can move further from the axis of rotation. This will, of course be counteracted by gravity. Nevertherless, it will be an effect present at the equator more so than at the poles.

This predicts that we should expect to see a flyby anomaly of some magnitude and that it will be correlated with proximity of a flyby to the equator.

Can anybody provide anomaly data and / or correlate it with angle of incidence in order to test this hypothesis?

  • $\begingroup$ I wish some expert here, would fix the weird typo or units here: en.wikipedia.org/wiki/Flyby_anomaly - what does "400–1000 m" mean?? $\endgroup$
    – Fattie
    Jul 15, 2016 at 20:16
  • $\begingroup$ Say Robert, great question. I personally would interpret your question thsi way: the possible explanations listed on Wikipedia ... en.wikipedia.org/wiki/Flyby_anomaly#Possible_explanations ... are old, out of date, and poorly curated. Would any experts in the field here have more up to date information about, what is currently considered the most likely cause? Great question! $\endgroup$
    – Fattie
    Jul 15, 2016 at 20:18
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    $\begingroup$ @JoeBlow I do actually think Wikipedia represents the current state of thinking. There's no known explanation so the opportunity exists for a bit of modeling and empirical testing. Brian Koberlein recently blogged that it's a mystery. $\endgroup$ Jul 15, 2016 at 21:07
  • $\begingroup$ thanks for that @robertfrost! i'm struggling to find that particular blog .. briankoberlein.com ??? $\endgroup$
    – Fattie
    Jul 15, 2016 at 21:24
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    $\begingroup$ User Hobbes at space.SE has an answer which says it's an unsolved problem in physics. $\endgroup$
    – Rob
    Aug 5, 2018 at 4:39


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