The current World Magnetic Model (released in 2015, meant to last until 2020) has slipped so far against reality that an early…

2019-01-14 IFTTT, Twitter, gregeganSF

The current World Magnetic Model (released in 2015, meant to last until 2020) has slipped so far against reality that an early update is needed.
Wikipedia describes the model as an order-12 spherical harmonic expansion of the magnetic potential, plus d/dt.https://t.co/QLhBnNiaOQ
— Greg Egan (@gregeganSF) January 13, 2019

(via http://twitter.com/gregeganSF/status/1084582451614146560)