Chapter 22 Notes:

Unit I: The Sun

• The sun is very dangerous to study
• Can be highly educational if studied correctly!
• Chinese astronomers were first to study the sun (first to notice sun spots)
• Galileo was the "father" of sun study.

• Went blind during the end of life!

1859 is when astronomers grasped the idea as to what the sun was composed of.

• Also identified its temperature and internal pressure
• A solar telescope is used to project an image of the sun onto the surface of a table top (much like a movie screen.)
• Satellites (like Solar Max) are also used to study the sun without interference from our atmosphere, etc.

Properties of the Sun:

• Our sun is an average sized star
• 1,380,000 km in diameter (110x earth)
• Sun’s volume could hold 1mil. Earths
• Weighs 6.5 sextillion tons (18 0’s?)
• 400x further away than our moon
• Concorde can fly from NY to Paris in 3½ hours ---- at same speed: 10 years to sun!
• Travel would take 8.3 minutes at the speed of light!
• Surface temp. = 5500 degrees C
• Interior temp. = ~ 15000000 degrees C

Sun’s Atmosphere:

• Composed of three major parts or layers
• Photosphere: bright yellow surface of the sun; about 400km thick
• Chromosphere: transparent red middle layer of the atmosphere
• Corona: Thin, outermost layer; up to 1 million km above the surface of the sun
• Solar prominences are huge, red, flamelike arches of material that occur in the corona; they may shoot millions of km above the surface

Sunspots are places on the surface where "burnout" has occurred; the "burnout" spots are not burnt our, but are areas that burn at much cooler temperatures. Up to 1500 deg. C cooler than the surrounding photosphere. Sunspots move over time also. They may last for many hours to many days.

Unit II: Observing the Solar System

• The sun’s family
• Every object in the system travels around the sun in an "orbit"
• Most orbits are circular, but a few are elongated.
• Five planets can be seen at different times of the year from earth…Mercury, Venus, Mars, Jupiter, and Saturn.

Solar System Models:

• 2000 years ago, people believed in what is called a "Geocentric" system
• This is identified as an Earth-centered system
• Copernicus proposed the "Heliocentric" system…or Sun-centered system
• All objects in the system orbit or revolve around our sun, not around earth