* Red Giant Phase: In about 5 billion years, the Sun will run out of hydrogen fuel in its core. This will cause it to expand dramatically, becoming a red giant. During this phase:
* Earth's fate is uncertain. The Sun will be much larger and hotter, likely engulfing Mercury and Venus. Earth's fate depends on how much the Sun expands and how much mass it loses.
* Even if Earth survives the engulfment, it will become uninhabitable. The oceans will boil away, and the surface will be scorched.
* White Dwarf Phase: After the red giant phase, the Sun will shed its outer layers, leaving behind a dense, hot core called a white dwarf. This is a much smaller and cooler object than the Sun is today.
* Earth will be a scorched, lifeless rock. It's unlikely to survive the red giant phase, but even if it does, the white dwarf Sun will be too weak to support life.
In short, the Sun's expansion into a red giant will likely mean the end of life on Earth as we know it. The white dwarf phase will be a much cooler and smaller Sun, unable to sustain life.
Important Note: This is a very simplified explanation. The exact fate of Earth is still being debated by scientists.
