Interesting article by Randy Miller from the Old Farmer's Almanac:
One-hundred-fifty years ago, on the night of September 1, 1849, the nearly full Moon appeared over the town of Canandaigua, New York. At 10:30 P.M., Samuel D. Humphrey slid a highly polished, silver-plated copper sheet measuring 2–3/4x1–3/4 inches into his camera, which was pointed at the Moon.
Humphrey then exposed the light-sensitive plate to the shining Moon nine times, varying the length of exposure from 0.5 seconds to 2 minutes. After developing the plate with mercury vapor, he sent his daguerreotype to Harvard College.
Louis Daguerre, the Frenchman who explained the secret of the world's first photographic technique in 1839, had daguerreotyped a faint image of the Moon, but the plate was soon lost in a fire. John W. Draper of New York City is credited with making the first clear daguerreotype of the Moon in March 1840, but this also was destroyed in a fire.
By 1851, the Harvard College Observatory was producing detailed, world-renowned daguerreotypes of the Moon, doubtless inspired by Humphrey, whose 1849 daguerreotype is now considered by many to be the earliest extant photograph of the Moon.