It is my understanding that Earth's Sun is a middle-age star moving into old age. Currently, Earth's Sun appears to be growing hotter, and consequently, its gravitational pull is getting stronger. Plans to use Earth's Moon as a launching site for travel to Mars seem predicated on belief of scientists that we need to make way for the Sun's expansion. But do we have factual knowledge, a tentative time table for the expansion and an estimate of how big the Sun will become (ditto for the contraction of the Sun). Perhaps subterranean towns can be constructed, like a gigantic "Noah's Ark" during the expansion and contraction. After all, humans lived in caves for 10,000 years during the Ice Age.
Dear Nancy Ann Watanabe ,
All stars die, and eventually — in about 5 billion years — our sun will, too. Once its supply of hydrogen is exhausted, the final, dramatic stages of its life will unfold, as our host star expands to become a red giant and then tears its body to pieces to condense into a white dwarf.
Reference :
https://www.livescience.com/62507-what-happens-when-sun-dies.html
Nancy, there is no evidence for the sun's present expansion nor any likelihood of it occurring in the near future. Should it do so we would fry in Mars one second after we fry on earth. The present hot weather globally might be due to increased solar activity but of course that is not the same. If humans last for another 5 million let alone billion years we will as a species be lucky but I expect we will discover our relatively unimportant nature and complete insignificance long before that.
Anyway, the earth will effectively die long, long before the sun does. Its water could be siphoned off, its atmosphere sucked away like cream on a coffee mug, and all that will be left is barran rock. We will end up a bigger Mars.