While teaching at Holmewood he set up a 12½ inch reflector telescope at his home, which he kept into his old age. He developed a particular interest in the far side of the Moon, a small part of which is visible from Earth as a result of the Moon's libration; the Moon was his specialist subject throughout his life. He claimed to have discovered and named the Mare Orientale (Eastern Sea) in 1946, along with Hugh Percy Wilkins, though he later conceded that German astronomer Julius Heinrich Franz should be credited with the discovery. The feature had been observed several times since telescopic observations began. Moore described the short-lived glowing areas on the lunar surface, and gave them the name transient lunar phenomena in 1968.