Observations on Stellar Extinction obtained in the Gemini 9 Space Flight

Abstract

LINK¹ has suggested that there is a high absorbing layer in the Earth's atmosphere. This layer, presumably dust, was suggested in order to explain the anomaly in the size of the Earth's shadow during eclipses. Some support for the suggestion came from measurements of stellar extinction from Mont Blanc². The height of the layer has been estimated as 100–150 km above the surface and it is presumed to have a vertical optical depth of 0.025–0.05. The purpose of this communication is to show that on the basis of stellar extinction measurements made in the Gemini 9 flight, no layer at an altitude above 80 km exists with a vertical optical depth of more than 0.0015. Either Link's layer does not exist at all or it is at a lower altitude than 80 km.