1. Solar Eclipse of 2017: On August 21, 2017, a total solar eclipse was visible in 14 states in the United States, including California. While California wasn't in the path of totality, residents were able to witness a partial eclipse that peaked at around 10:15 a.m. PST.

2. California Statehood: August 21, 1850, marked the official admission of California as the 31st state in the United States of America. This was a result of California's rapid population growth due to the gold rush, which led to the need for statehood.

3. "Seinfeld" Pilot: On August 21, 1989, the first episode of the iconic television show "Seinfeld" premiered on NBC. Created by Larry David and Jerry Seinfeld, the show went on to become a cultural phenomenon, influencing television and popular culture for years to come.

4. The Earp Brothers and the Gunfight at the O.K. Corral: On August 21, 1879, the Earp brothers, along with Doc Holliday, engaged in a gunfight with a group of cowboys at the O.K. Corral in Tombstone, Arizona. While not directly taking place in California, the Earp brothers were California lawmen, and the events of the gunfight eventually led to their return to California and a decades-long feud known as the Earp Vendetta Ride.

5. San Francisco Earthquake and Fire: On August 21, 1915, the Pan-Pacific International Exposition opened in San Francisco. Unfortunately, this event was overshadowed by the devastating earthquake and subsequent fires that destroyed a large portion of the city five years earlier, on April 18, 1906. The Pan-Pacific International Exposition was held to celebrate San Francisco's recovery and to showcase the city's resilience.