1. Size, Heat, and Structure
The Sun
Size, Heat, and Structure

2. Worship me in all of my hotness.

3. But First…
What is the significance of these numbers when discussing the Sun?
1.3 million
109 8
93 million 1

4. Objectives Explain the structure of the sun and its energy source.
Describe the effects of sunspots, solar wind, and magnetic storms on Earth and explain the role of Earth’s magnetic field.

5. And as we study the sun today, consider this.
How does the sun’s size, heat, and structure affect Earth?

6. Everyone knows that it takes 8 minutes and 20 seconds for light from the Sun to reach us on Earth…but how BIG is the Sun?

7. Size of the Sun The Sun is enormous compared to Earth.
Diameter of 1,400,000 km (more than 3x the distance from Earth to the moon; which is the longest distance humans have traveled in space)

8. How many Earths would fit inside a hollow sun?

9. Over one million!

10. How long would it take a jet to circle the Sun?
2 months
That is if you were flying at Mach 3 (3 times the speed of sound)

11. But remember… The Sun is an average sized star.
The largest known star, Epsilon Aurigae, is 4,000 x larger than the sun.

12. Our sun is known as a: Main Sequence Star

13. Where does the Sun get its energy?
Fusion -- the combining of lighter elements to form a heavier one.
Hydrogen atoms are fused into Helium atoms.

15. Hydrogen atoms fuse together to make a helium atom.
But a neutron is released along with a lot of energy.
This left over matter becomes energy. (E=mc2).

17. You da man Albert!

18. The matter that makes up the sun is very high energy gas under intense heat and pressure.
This matter is plasma.
Plasma – the fourth state of matter that consists of flowing electric charge

19. The Sun’s Layers
No one has observed the interior of the sun but models have been produced.
The energy produced inside the sun pushing outward is balanced by the gravity drawing the outer layers inward.

20. The Sun’s Core
The plasma in the core, made mostly of hydrogen and helium, is 100x more dense than water.
Temp = 15,600,000 degrees C

21. Radiative Zone
Another layer of plasma that is cooler and just outside the inner core.
8,000,000 deg C

22. Convection Zone
1,500,000 deg C
Rising and falling currents of plasma carry energy to the sun’s surface where it is radiated out into space as sunlight

24. Photosphere
The visible surface of the sun
6,000 deg C

25. Chromosphere The sun’s “atmosphere”
Thousands of kilometers above the photosphere
20,000 deg C
This high temperature causes the hydrogen to emit reddish light.

27. Corona The thin outer part of the sun’s atmosphere
A million times less bright than the photosphere
Still hot at 1,000,000 oC
The Corona is the HOTTEST layer of the atmosphere.

28. What features of the sun are visible during a solar eclipse?
The Corona and the chromosphere

30. Sunspots The sun rotates.
Scientists are able to prove this because sunspots appear to move!
Dark spots on the photosphere
Some are barely visible
Some are 4x the size of Earth

31. What causes sunspots?
Sunspots occur where the sun's magnetic field loops up out of the solar surface and cool it slightly, making that section less bright.

34. Sunspots are actually pretty hot and bright.
But they are dark because the surrounding photosphere is so much hotter and brighter.
Sunspots are 3,000 o C and the sun’s surface is 6,000 oC.

35. The Sunspot Cycle
Sunspots go through periods of high and low activity.
Peak activity happens every 11 years or so.

36. Why study sunspots?
They can tell us things about the Sun’s magnetic properties.
And, because someone wants to!

37. Solar Wind A constant stream of electrically charged particles
These particles are mostly protons and electrons
Luckily, the Earth has its own magnetic field that deflects solar wind and solar flares

38. Why would solar flares and solar wind be harmful to us?
These charged particles could cause cancer.
Growth of all living things would be inhibited.
As solar wind blows past earth, particles interact with the earth’s upper atmosphere producing a display of colors called…..

39. Auroras Beautiful displays of color and light appearing in the sky
They occur when solar wind interacts with the magnetic fields of the Earth in the upper atmosphere.
Also called the Northern Lights or Southern Lights

43. Magnetic Storms
In March 1989, the sun emitted a huge solar flare that made TV receptions fade, caused power outages, and made garage doors malfunction.
National Geographic Solar Blast

44. Why does the sun look red sometimes?
When the Sun is low on the horizon, its light has to travel farther to reach you. This allows red, a longer wavelength, to be seen.
When the Sun is high on the horizon, blue light is scattered, which allows you to see a yellow sun.

45. When will the Sun die?
The sun is now 4.5 billion years old and will die (burn out of fuel) in 5 billion years.
It will go from a red giant to a yellow dwarf.
It will get so big at the end of the giant stage that its diameter will likely reach Earth’s orbit.
Better get cho SPF on?!

46. National Geographic Video
The Sun 101
National Geographic Video