Review Day
Drill: List three things you know about a
star that you did not know prior to the unit.
Objective: SWBAT identify concepts
presented in the astronomy unit on stars
unit in order to prepare for the test.
HW: STUDY
Characteristics of a Star
 Scientists classify stars based on several
characteristics:
Color & Temperature:
 Red = Cool & Blue/White = Hot
Brightness (luminosity)
 Absolute magnitude vs. Apparent magnitude
Size (Group)
 Main Sequence
 White Dwarf
 Giant
 Super Giant
Hertsprung-Russell Diagram
The H-R Diagram show the relationship
between temperature and brightness.
Identifies four characteristics of stars
Temperature
Brightness
Color
Category
Star Facts
Lifespan of a star is determined by it’s
size.
Large stars have short life spans
Small stars have longer life spans
Brightness is determined by size and
surface temperature.
Only the largest stars (40 times the size of
our sun) will become black holes.
Protostars are early stars before nuclear
fusion occurs
Parts of the Star
The sun is made mostly of Hydrogen(75%)
and Helium (25%).
The sun has 3 parts to the body:
Core: Dense area where nuclear fusion occurs
burning at about 15 million degrees F
Radiation Zone: Heat travels outward through
the zone to the next layer.
Convection Zone: Area where currents of
heated materials transfer heat to the exterior
and carry cooler area in.
Parts of the Atmosphere
The atmosphere that surrounds the sun is
made of three layers:
Photosphere: Area where light is given off and
lowest portion of the atmosphere.
Chromosphere: Area beyond the photosphere.
Corona: Only visible portion of the sun during
an eclipse and the furthest layer from the core.
Galaxies
Galaxy: Collection of gas, dust, and
stars held together by gravity.
There are 3 types of galaxies:
Spiral: Pinwheel shape with stars on the arms
and gas and dust clustered in the center.
Thought that a black hole is in center.
Elliptical: Flat, pancake shape that produces
a beacon of light. Lots of old stars but little
gas and dust
Galaxies con’t
Irregular: No definite shape. Lots of gas
and dust with very old stars.
Explosions from supernovas caused these
galaxies to lose their shape.
Oldest/Youngest known type of galaxy.