Which astronomer discovered Titan's atmosphere in 1944?

Gerard Kuiper discovered Titan’s atmosphere in 1944 by detecting methane with spectroscopy.

Kuiper studied sunlight reflected from Titan and passed its spectrum through an instrument that separates light into its component wavelengths. The resulting absorption features revealed methane, demonstrating that Titan was enveloped by a substantial atmosphere rather than being a bare, airless moon.

His initial estimate placed Titan’s methane partial pressure at roughly 100 millibars. Later observations, especially from spacecraft and improved telescopic instruments, showed that his estimates of methane abundance and surface pressure were too low. Titan’s atmosphere is now known to be chiefly nitrogen, with methane as an important minor constituent.

The discovery is often confused with the earlier discoveries of Titan itself and Saturn’s other moons. Christiaan Huygens discovered Titan in 1655, while Giovanni Cassini discovered several Saturnian moons and ring features. Kuiper’s 1944 achievement was identifying Titan’s atmosphere spectroscopically.