Astronomy
Name _________KEY____________
Sun Notes
Copy the picture of the sun’s layers the teacher has for you (Zeilik Text pp 283-294, or go to
http://www.shef.ac.uk/physics/people/vdhillon/teaching/phy213/phy213_properties_intro.html).
Draw and/or label the following:
Core
Corona
solar wind
chromosphere
sunspot
Photosphere
radiative zone convection zone
solar flare
prominence
1. In the ___core__, hydrogen is fused into ___helium_____.
2. A __sunspot____ is a dark area of the sun that is cooler than the surrounding area.
3. _Solar wind__ is made of charged particles that continually escape from the corona and
move through space.
4. A _prominence_ is found above the photosphere and is shaped by magnetic field lines.
5. A sudden burst of electromagnetic energy caused by magnetic disturbances produces a
__solar flare__.
6. The sun has three atmospheres: _photosphere_, _chromosphere_, and __corona___.
7. The _photosphere__ is the lowest layer of the sun’s atmosphere from which light is given
off.
8. Just above the photosphere is the colored part of the sun called the _chromosphere__.
9. The chromosphere is pierced by _spicules_ which look like a rolling, boiling fire.
10. The outermost, and HOTTEST, region of sun’s atmosphere is the __corona__.
Temperatures reach _1 million_ K, and it reaches out thousands of miles.
The Sun’s Interior (Zeilik text pp. 287-291)
1. Two processes transfer heat energy in the Sun: __radiation__ and ___convection__.
2. The core makes up __25%__ of the Sun’s radius, and about ___99%__ of the Sun’s mass
lies within 60% of the Sun’s radius.
3. The radiative zone extends out to _80%_ of the Sun’s radius. Photons travel slowly
through this zone, and they can take __thousands___ of years to reach the Sun’s surface.
4. The outermost __20_% of the Sun’s radius is less dense, and heat is transferred by
__convection___, much like the Earth’s mantle.
Nuclear Fusion
5. Energy is produced in the Sun by fusing _hydrogen__ into _helium__ in the core.
6. This is the equation for hydrogen fusion:
4 H  He + 2
7. Einstein showed that energy and mass are convertible by the equation:
E = m c2
8. In the equation above, c = light speed (186,000 miles/sec or 300,000 km/s), so a very
small mass (on the product side of fusion) can create a very large amount of energy.
9. The minimum temperature needed for fusion to occur is _8,500,000oC (our Sun’s core is
estimated to be __15,000,000_oC.
The Sun’s Magnetism
10. The Sun has an intense magnetic field, which is the suspected cause of __sunspots__,
___prominences___, and ___solar flares__.
11. The polarity of the Sun (N-pole – S-pole) reverses in a(n) __11_ year cycle.
12. One explanation for the Sun’s active magnetic field is its _differential __ __rotation___,
the Solar poles rotate __slower___ than the equator. Poles = 31 days; equator = 25 days