Gender of nouns in Spanish II exceptions to the rule of the ending "o" and "a"

In a previous post we mentioned that, in Spanish, most nouns ending in "o" are nasulines and most nouns ending in "a" are feminine. That's true, but there are important exceptions to that rule. 

On the one hand, there are some nouns that end in "o" and are feminine, and others that end in "a" and are "feminine". Here are a few examples: 

Feminine nouns ending in "o": moto (motorcycle), foto (photo), mano (hand), radio (radio)

"Caso Barrera: buscan al conductor de la moto desde la cual partió el disparo mortal" (Barrera case: they are looking for the driver of the motorcycle from which the fatal shot was fired). The noun "moto" is preceded by the definite article "la", because it is feminine. 

Masculine nouns ending in "a": día (day), clima (weather), problema (problem), mapa (map), poema (poem), planeta (planet), fantasma (ghost).

"10 perfumes suaves y elegantes que duran todo el día (y no son los típicos)": 10 soft and elegant perfumes that last all day (and are not the typical ones). The noun "día" is preceded by the definite article "el" because, although it ends in "a", it is masculine.