Answer: change in solar output.
 
        
             
        
        
        
Well theory isnt proven. It means you have a strong idea about the subject your talking about. So if a scientist finds evidence that suggests something against the theory then it can be changed. 
        
                    
             
        
        
        
Known as the cell’s “command center,” the nucleus is a large organelle that stores the cell’s DNA (deoxyribonucleic acid). The nucleus controls all of the cell’s activities, such as growth and metabolism, using the DNA’s genetic information. Within the nucleus is a smaller structure called the nucleolus, which houses the RNA (ribonucleic acid). RNA helps convey the DNA’s orders to the rest of the cell and serves as a template for protein synthesis.
        
             
        
        
        
The three large arteries originating from the aortic arch are the brachiocephalic trunk<span>, left </span>common carotid artery<span>, and left </span>subclavian artery<span>.</span>