of about 10 billion years, current estimates put our Sun at 4.6 billion years. It does not run on "fuel" it runs on nuclear reaction and needs no traditional fuel to "burn". If the time stream in WoT is truly cyclical then the sun in theory would never burn out as it would be in a loop not allowing for change. Human fires burn on fuel, which by nature are finite. However, an tied off weave of fire also burns perpetually with no need of fuel beyond the OP. It seems unlikely that the sun is a mega weave ... Thus the time loop seems more likely to me ... It's not particularly relevant, just an observation based n the RJ quote.