If the sun increases in size and becomes so big, can it engulf the entire earth into it, in the next 5 billion years?

Is this possible ?

  • $\begingroup$ Is this really on topic? Seems to be just a scientific question about the actual future. $\endgroup$
    – user16107
    Mar 21, 2016 at 10:19
  • $\begingroup$ What do you mean "is this possible" ? You probably read it from some source, explaining the expansion of the dying Sun. Why wouldn't it be "possible"? Can you clarify what you asking? $\endgroup$ Mar 21, 2016 at 10:39
  • $\begingroup$ This should be in the astronomy stack exchange. $\endgroup$
    – Murphy
    Mar 21, 2016 at 12:30
  • 1
    $\begingroup$ In case you needed a reference: en.wikipedia.org/wiki/Sun#After_core_hydrogen_exhaustion $\endgroup$
    – cobaltduck
    Mar 21, 2016 at 13:15
  • $\begingroup$ @cobaltduck I really needed that reference. The first paragraph just says everything . Thank you very much $\endgroup$ Mar 22, 2016 at 4:54

1 Answer 1


The red-giant sun will expand to the present orbit of the Earth.

Meanwhile, since it blows off some mass, the Earth will back away slightly.

So, it's an open question as to whether Earth will fall in, or be vaporized before friction gets it, and in the latter case it's possible that some of the iron core would survive.

For setting a story, you can choose either case and write plausible hard SF.

  • 2
    $\begingroup$ Current models suggest that the Sun will eventually engulf the Earth but it is still an open question en.wikipedia.org/wiki/Future_of_the_Earth#Red_giant_stage. So as JDlugosz said, you can easily write your story to go either way. $\endgroup$
    – Jim2B
    Mar 21, 2016 at 14:09
  • $\begingroup$ @Jim2B This link is just so useful and got more interesting information, "Another scenario is that Earth somehow survives being engulfed to the Sun, but that the ablation and vaporization mentioned before will strip both its crust and mantle leaving just its core." Thank you $\endgroup$ Mar 22, 2016 at 4:56

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