Arda brukar ofta användas i bemärkelsen "jorden", men enligt Tolkien är ju Arda något mer, som i fysisk bemärkelse snarare är "solsystemet". Vad ska man då kalla "jorden"?
I not 2 i "Athrabeth Finrod ah Andreth" ur Morgoth´s ring skriver Tolkien:
Citera:
Arda, or 'The Kingdom of Arda' (as being directly under the kingship of Eru's vice-regent Manwë) is not easy to translate, since neither 'earth' nor 'world' are entirely suitable. Physically Arda was what we should call the Solar System. Presumably the Eldar could have had as much and as accurate information concerning this, its structure, origin, and its relation to the rest of Ëa (the Universe) as they could comprehend. Probably those who were interested did aquire this knowledge. Not all the Eldar were interested in everything; most of them concentrated their attention on (or as they said 'were in love with') the Earth.