As the humans go about their affairs, living atop a thin crust floating on molten rock, the liquid iron in the Earth’s core is churning in strange, erratic ways.

This is a problem because those humans, clever in some ways, have figured out that the movement of the liquid iron creates a magnetic field. For centuries, their compasses have pointed “north.” But where that is, exactly, is changing.

After observing, if not exactly understanding, the magnetic field’s recent behavior, scientists decided to update the World Magnetic Model, which underlies navigation for ships and planes today. As Nature reported, the update was supposed to come January 15. But the model is jointly developed by the British Geological Survey and the U.S. National Oceanic and Atmospheric Administration, and the U.S. government is shut down.

The NOAA web page for the World Magnetic Model currently says, “The website you are trying to access is not available at this time due to a lapse in appropriation.”

Read: The upheaval at the end of the world

This isn’t a big crisis: The north magnetic pole has always drifted. Since scientists began tracking its location in the 19th century, it has moved from Canada toward Siberia. (The north magnetic pole is close to but distinct from the north geographic pole, whose location is determined by the axis on which the Earth spins.) For most of the 20th century, the pole moved about nine miles a year. Then, beginning in the 1990s, it moved about 35 miles a year.