Hello! Socratic's Terms of Service and Privacy Policy have been updated, which will be automatically effective on October 6, 2018. Please contact hello@socratic.com with any questions.

The Sun

Key Questions

  • Answer:

    When the sun runs out of hydrogen to fuse, it will start fusing helium into heavier and become a red giant. After it has run out of helium, it will expel its planetary nebula and become a white dwarf.


    Our sun is currently a main-sequence star of relatively common occurrence and is fusing hydrogen into helium, producing a massive amount of energy every second.

    Scientists estimate that the sun has about 5 billion years left on the main sequence- after which our sun will become a red giant-engulfing the inner planets, including Earth. However, it is not massive enough to become a supergiant, nor collapsing into a black hole- but will instead become a white dwarf after the red giant runs out of helium to fuse- but this will take approximately another 10 billion years before occurring.

  • Answer:

    Sun is a main sequence star G2 v type spectrum,


    main elements
    Hydrogen 73.4%
    Helium 24.8
    Oxygen 0.7%
    Carbon 0.29%