You are right the earth is expanding but not just because of the sun. It is because we are and have been going through a galatic wave of suatomic particles that pass into the center of our earth and other bodies in our system even the sun is bieing affected. This does happen in cycles there is a least afected 11800 year cycle and the more extream 26000 year cycle. These suatomic particle's are comming from the center of our galaxie in waves like you see our sun expelling waves on soho link . these suatomic particles enter react with our core and other bodies to produce matter in greater quanties at given times. i think if you think of our system all of it as a recycling plant as matter such as stars and other forms bieing asorbed by a black hole it compresses this into subatomic particles and expells it back out into the galaxie. to reform more matter . This also does have to do with our place in the galatic plane. thats why it's divided into 2 cycle's 11800 and 26000 . if this gives you some food for though then good if not ok.