July 23

Monday 23, 1973:

Robert Anton Wilson, the occultist/philosopher, either achieved contact with extraterrestrials from Sirius or started a long-term period of having wild hallucinations, depending on which way you want to look at it.

Sunday 23, 1972:

The United States launches Landsat 1, first Earth-resources satellite.

Thursday 23, 1903:

Dr. Ernst Pfenning of Chicago, Illinois becomes the first owner of a Ford Model A.

Wednesday 23, 1862:

American Civil War: Henry W. Halleck takes command of the Union Army.

Thursday 23, 1503:

Orbital calculations suggest that on this day Pluto moved outside Neptune's orbit, remaining there for 233 years.