Current-Sheet Thickness Compared with the Ion Inertial Length in the Magnetotail and at the Magnetopause

This paper examines current-Sheet Thickness Compared with the Ion Inertial Length in the Magnetotail and at the Magnetopause using representative published values, with every headline quantity evaluated numerically in an accompanying calculation script. The principal findings are that tail density cm3 = 0.3, tail ion inertial length km = 416, and tail observed sheet thickness km = 1000. The analysis states its assumptions explicitly, tests how the conclusions move when the inputs vary across their published ranges, and identifies the measurement that would most improve each estimate. The results are presented as scales, ratios and bounds, as appropriate to each quantity, rather than as precise predictions for individual events.