Celebrated on August 27 of each year, Mars Hoax Day originated in an 2003 e-mail that claimed Mars would be so close to earth on the 27th day of August that it would appear in the night sky as large as the full moon. The email fooled people into scanning the night sky for a supersized Mars. It just so happened that the same hoax message returned the next year and thus creating a tradition.

The original Mars Hoax Day may not have been intentional. An email message reported that Mars and Earth in 2003 were the closest they had been in close to 60,000 years. The message was misinterpreted to mean that Mars would appear very large. Subsequent exaggerations spread like wildfire as people forwarded the message to their friends and colleagues.