Hmmm...did I say gobble?<br /><br />Well, most assumptions I've read suggest the Sun's red giant phase could see expansion 50 - 200 times its current diameter. But then I thought about your statement and put some numbers around what that means...<br /><br />So for my answer this time I'll do a little math.<br /><br />Sun's diameter: 1.4 x 10^6 km<br /><br />Current Saturn-Sun distance: 9.8 AU where 1 AU = 150,000,000 km (approximate)<br /><br />so distance to Saturn from the Sun = 1,470,000,000 km.<br /><br />If I consider a red-giant phase expansion of 200x then the solar diameter becomes 280,000,000 km<br /><br />If I consider a red-giant phase expansion of 100x then the solar diameter becomes 140,000,000 km<br /><br />If I consider a red-giant phase expansion of 50x then the solar diameter becomes 70,000,000 km<br /><br />Then, assuming Saturn's distance remains the same: <br /><br />Distance from expanded Sun to Saturn:<br /><br />50x scenario: 1,400,000,000 km<br />100x scenario: 1,435,000,000 km<br />200x scenario: 1,330,000,000 km<br /><br />So, the change we see is not actually a gobble but a minor warming!!!<br /><br />As the Sun expands it will also lose mass. This could cause the orbits of the planets to change. But allow me to assume Saturn's orbit doesn't change (big assumption). But for convenience I'll keep that 9.8 AU distance for Titan and look at heat flux. Using the inverse square law I'll be basing my calculation on current earth-normal flux (1370 watts / m^2) falls on Earth from the Sun. <br /><br />Saturn, in the 200x expansion scenario, is 1,330,000,000 or about 8.8 AU from the Sun. 8.8 AU is 8.8 TIMES the current Earth-Sun distance. Using inverse-square law the solar flux is <br /><br />(Intensity at Earth) / (Distance squared) as derived from I=S/4(pi)r^2<br /><br />So, I = 1370 / (8.8)^2 = 1370 / 78.6 = 17.5 watts per m^2!<br /><br />In the other scenarios the heating is less.<br /><br />Of course, I do not have a value for S if the sun is a red giant, only the S value as the <div class="Discussion_UserSignature"> </div>