Atharvaveda 6.8 is called Kãmãtma Sukta (or Hymn to fulfill desire). It was heard by sage Jamadagni.
The first line of 6.8.3 is as:
यथेमे द्यावापृथिवी सद्यः पर्येति सूर्यः ।
yatheme dyāvāpṛthivī sadyaḥ paryeti sūryaḥ ।
The meaning is as:
यथेमे (yatheme) = Just like
द्यावापृथिवी (dyāvāpṛthivī) = Earth and Heaven
सद्यः (sadyaḥ) = Immediately
पर्येति (paryeti) = Reaches
सूर्यः (sūryaḥ) = Sun
As the word 'सद्य' / 'Sadya' is used there which means 'Immediately'. So it is referring to the 'Light of Sun'. As it is light of Sun which reaches immediately. So, the meaning is:
Just as light of Sun reaches immediately Earth and Heaven...
In anycase if one interprets it as 'Sun' only also then it doesn't matter because the verse is nowhere talking about revolution of sun towards earth.
And Vedas do not propagate the idea that rising and setting of sun is due to revolution of Sun towards earth. For eg. RigVeda Aitreya Brahmana 3.44 states:
एष न कदा चनास्तमेति नोदेति
eṣa na kadā canāstameti nodeti
This (Sun) never rises and never sets.