More Information
Source
Grolier Online
Discover the content connection—the definitive, fully integrated database collection and online research portal. It includes seven encyclopedia databases: Encyclopedia America, Grolier Multimedia Encyclopedia, The New Book of Knowledge, La Nueva Enciclopedia Cumbre, America the Beautiful, Lands and Peoples, and The New Book of Popular Science.

Structure of the Sun: Inner Core

Structure of the Sun
From its innermost core to its corona and to the solar wind that extends far past the Earth, the Sun has a structure typical of most stars of its kind.

Inner Core. The weight of the Sun's outer layers compresses the gas of the innermost region to a density about 100 times that of water and raises the central temperature to about 15 million K (27,000,000° F). Throughout the Sun's interior, atoms collide frequently and with enough energy to ionize the gas, which is then referred to as a plasma. In the inner third of the Sun the collisions among ions are energetic enough to cause nuclear reactions at a rate sufficient to liberate the energy required to give the Sun's observed luminosity. The specific set of reactions thought to be most effective in generating energy in the Sun involves the burning of hydrogen to helium, following the specific sequence of reactions known as the proton-proton reaction. Present evidence suggests that the plasma of the central nuclear burning region of the Sun is not mixed with the material in the outer shells. Thus the proton-proton reaction will continue only until the hydrogen of the central region, some 10% of the Sun's mass, becomes transformed into helium after about 10 billion years. The Sun's age is estimated to be about 5 billion years. The gamma rays and X rays emitted by the nuclear reactions travel outward with little absorption through the solar interior, because the electrons that allow an atom to absorb light have mostly been stripped from the nuclei by interatomic collisions.

  • Teacher Store
  • The Teacher Store  
    1000 Facts about Space

    1000 Facts about Space

    by Pam Beasant

    This colorful, oversized book is packed with facts on stars, moons, comets, planets, and more—plus sections on ancient and modern astronomy as well as the future of space exploration.

    $5.21 You save: 25%
    Paperback Book | Grades 4-8
    Add To Cart
    Educators Only
    1000 Facts about Space
    Grades 4-8 $5.21
    Add To Cart
  • Teacher Store
  • The Teacher Store  
    Take a Giant Leap, Neil Armstrong! - Literacy Fun Pack Express

    Take a Giant Leap, Neil Armstrong! - Literacy Fun Pack Express

    Scholastic After School Literacy Fun Packs Express pair five copies of one of our engaging nonfiction or fiction titles with a one-hour lesson plan – perfect for after school or out-of-school time. The lessons are simple to implement and require little to no preparation time. Perfect for small group read-alouds and aligned to Common Core State Standards, our Literacy Fun Packs Express provide discussion questions, reading tips, and a variety of hands-on activities to promote additional student inquiry.

    Eager young readers will learn amazing anecdotes about the earliest accomplishments of some of America's greatest leaders in these accessible, easy-to-read chapter books.


    Set Includes:
    • Take a Giant Leap, Neil Armstrong! (Roop)
    • Take a Giant Leap, Neil Armstrong! (After School Teaching Card)


    Click here to learn more about Afterschool Learning.

    $19.99
    Paperback Book Collection | Grades K-2
    Add To Cart
    Educators Only
    Take a Giant Leap, Neil Armstrong! - Literacy Fun Pack Express
    Grades K-2 $19.99
    Add To Cart
Help | Privacy Policy
EMAIL THIS

* YOUR NAME

* YOUR EMAIL ADDRESS

* RECIPIENT'S EMAIL ADDRESS(ES)

(Separate multiple email addresses with commas)

Check this box to send yourself a copy of the email.

INCLUDE A PERSONAL MESSAGE (Optional)


Scholastic respects your privacy. We do not retain or distribute lists of email addresses.