Earth's magnetic storms can selectively hide certain cosmic events while leaving normal stars perfectly visible on old photographic plates.
April 23, 2026
Original Paper
Stellar Detection Counts Are Invariant Across Geomagnetic Storm Intensity in POSS-I Plates: Ruling Out the Plate Sensitivity Artifact and Confirming Source-Specific Transient Suppression
arXiv · 2604.16470
The Takeaway
Geomagnetic storms were long suspected of simply making photographic plates less sensitive to all light. Analyzing thousands of plates shows that stable stars remain clearly visible during these storms even as fast-moving transients vanish. This proves that the storms are not causing a general equipment failure or artifact on the film. A mysterious interaction between the Earth's magnetic field and specific types of astronomical signals appears to be suppressing our view of the deep sky. Solving this mystery could reveal that we have been blind to a whole category of rare cosmic explosions during periods of high solar activity.
From the abstract
The VASCO project has identified over 100,000 optical transients on photographic plates from the First Palomar Observatory Sky Survey (POSS-I, 1949-1957). Cann (2026a) demonstrated a dose-dependent suppression of transient detection rates across five geomagnetic storm intensity (Kp) bins (Cochran-Armitage: Z = -3.391, p = 0.0007, 3.4 sigma). A principal objection to this finding is that geomagnetic storms enhance atmospheric airglow, reducing overall plate sensitivity and thus suppressing detect