Earth Science

Earth in Space

Interior of the Sun

Study Tip
How would scientists use cameras to observe different layers of the Sun? Hint: Different temperatures are associated with different wavelengths on the electromagnetic spectrum!

The Sun

  • The Sun is a sphere, composed almost entirely of the elements hydrogen and helium.
  • The Sun is not solid, nor is it a typical gas.
  • It does not have a defined outer boundary.
  • It does have a definite internal structure with identifiable layers.
  • Most atoms in the Sun exist as plasma.
  • Fourth state of matter made up of superheated gas with a positive electrical charge.
Study Tip
How would scientists use cameras to observe different layers of the Sun? Hint: Different temperatures are associated with different wavelengths on the electromagnetic spectrum!

Internal Structure

From inward to outward, the layers of the Sun are:

  • Central Core
  • Plasma with a temperature is around 27 million ⁰C.
  • At high temperatures hydrogen goes through nuclear fusion, which forms helium
  • This energy moves outward, towards outer layers of the Sun.
  • Radiative Zone
  • Temperature of about 7 million ⁰C.
  • Energy from core travels extremely slowly through here.
  • Photons (particles of light) travel only a little before they hit another particle.
  • The photon is absorbed and then released again.
  • Convection Zone
  • Hot material from near the radiative zone rises, cools at the Sun’s surface, and plunges back downward to the radiative zone.
  • Convective movement helps to create solar flares and sunspots.
Central Core of Sun

The Outer Layers

There are no solid layers to any part of the Sun’s atmosphere; these boundaries are fuzzy and indistinct.

  • Photosphere
  • The photosphere is relatively cool (6,700 ⁰C).
  • Visible surface of the Sun.
  • Region that emits sunlight.
  • The photosphere has several different oranges, yellow and reds.

Earth Science

The Outer Layers Cont.

  • Chromosphere
  • Temperatures range from about 4,000⁰C to about 10,000⁰C.
  • Jets of gas speed up 72,000 km per hour & are 10,000 km high.
  • Thin zone (2,000 km thick).
  • Glows red as it is heated by energy from the photosphere.
  • Corona
  • Temperature of 2~5million ⁰C (much hotter than photosphere).
  • Outermost plasma layer.
  • It is the Sun’s halo or "crown."
Concept Check
  • What is the Sun made out of?
  • What are the different zones and where are they located?
  • What kinds of fusion occur in the central core?
  • Describe the behavior of photons in the radiative zone.
  • What does the photosphere emit?