amaterasu would burn the chakra and you only need air to feed fire and amaterasu is not a normal fire and vacuum would not work (the sun is an example)
amaterasu would burn the chakra and you only need air to feed fire and amaterasu is not a normal fire and vacuum would not work (the sun is an example)
The sun doesn't burn you know...
The sun "burns" by creating a series of thermonuclear explosions to produce helium nuclei that are emptied onto space. Meaning the sun does not produce energy through combustion (which is burning or fire), but instead the division of atoms: more specifically the nucleus or smallest unit of the atom.
Fire is simply a visible description of a combustion reaction in which there is actually thermochemistey (fire). However, to keep producing such a flame, one has to have the presence of Oxygen: Burning compound plus O2 ==> H2O and CO2.
Amaterasu is by no means a normal flame; however, it operates on basic thermochemical properties.
A vacuum is a place in which NOTHING exists. Amaterasu is designed to burn what it is contacting; however, it cannot pass through nothingness. Thus, it would only be capable of burning chakra or it wouldn't form. Amaterasu is a projectile yet doesn't burn the air. Thus, if fired at a vacuum it would not work: because it can't burn nothing. And it doesn't burn air.
Like you said, Amaterasu would only burn the chakra.
If you want to debate it, Quote me instead of just commenting bluntly. And let me know when you do post: unlike OPB, I don't get a notification for quotes.