IAU definition of planet who had theorized on the existence of the large trans-Neptunian object Planet X, and Tombaugh been searching for Planet X when he found Pluto. Almost immediately after its discovery, however, astronomers questioned whether Pluto could be Planet X. Willy Ley wrote a column in 1956 titled "The Demotion of Pluto", stating that it "simply failed to live up to the advance publicity it received as 'Planet X' before its discovery. It has been a disappointment all along, for it did not turn out to be what one could reasonably have expected". In 1978, Pluto's moon Charon was discovered. By measuring
Atmosphere of Pluto it was possible to calculate its distance from Pluto's center. Subtracting the modern figure for the radius of Pluto, the result is a height of ; hence this "haze" is indistinguishable from the surface of Pluto. During later occultations (when the atmosphere of Pluto was already denser) this kink was absent. Another evidence of the haze was obtained in 2002 due to a new occultation. The stellar light which managed to reach Earth during the occultation (due to refraction in Pluto's atmosphere), demonstrated an increase of intensity with wavelength. This was interpreted as a reliable evidence of light scattering by