According to standard scientific predictions, the Sun will become a red giant in about 5 billion years. When that happens life on Earth would be impossible — in fact, as a red giant the Sun would expand to large than the Earth’s current orbit, so there would be no Earth.
The Bible, of course, says nothing about any of this, presumably because it is not an issue. God created the universe therefore it will not be any problem for God to recreate the Earth, the Sun or anything that needs to be recreated for his plan for humanity to be realised.
“5 They shall fear thee as long as the sun and moon endure, throughout all generations.” (Psa 72:5 KJV)
“17 His name shall endure for ever: his name shall be continued as long as the sun: and men shall be blessed in him: all nations shall call him blessed.
18 Blessed be the LORD God, the God of Israel, who only doeth wondrous things.
19 And blessed be his glorious name for ever: and let the whole earth be filled with his glory; Amen, and Amen.”
(Psa 72:17-19 KJV)