#3. Earth is the only planet not named for a mythological god or goddess
The other seven planets in the solar system were named after Roman gods or goddesses. For the five
visible to the naked eye, Mercury, Venus, Mars, Jupiter and Saturn they we named during ancient times.
This Roman method was also used after the discovery of Uranus and Neptune. The word “Earth” comes
from the Old English word “ertha” meaning ground or land. Source: universetoday.com