July 23

1972 – The United States launches Landsat 1, the first Earth-resources satellite.
1995 – Comet "Hale–Bopp" is discovered, though it becomes visible to the naked eye on Earth almost a year later.
2015 – NASA announces discovery of planet "Kepler-452b," a possible Class M world 1,800 light years away from Earth.
2037 – The Earth spaceship ESS Charybdis, commanded by Colonel Stephen G. Richey, is launched as the third attempt to explore beyond the Sol system.