Download Space Science Unit

Introduction Activity
• You are stranded on the
Moon and you have 15
items to choose from.
You must decided
which ones are most
important to take with
you. Rank these items
in order from 1-15, 1
being most important
and 15 being the least
important.
Stranded on the Moon:
•
•
•
•
•
Box of Matches
Food Concentrate
50 feet nylon rope
Parachute silk
Solar Powered Heating
Unit
• Two .45 Caliber Pistols &
Ammunition
• One case- Evaporated
Milk
• Solar Powered FM
receiver-transmitter
• Two 100-lb. tanks of
oxygen
• Stellar Map
(constellations as they
appear from the moon)
• Self-Inflatable Life Raft
• Magnetic Compass
• 5 gallons of water
• Signal Flares
• First Aid Kit- Containing
Injection Needles
Space Science Unit
Mini-lesson
Introducing the H-R Diagram
What is the H-R Diagram?
What does it do?
• This chart uses surface temperature of the
star and the absolute magnitude (brightness)
of the star to help astronomers decide which
phase of the star’s life cycle the star is in
and other important information about the
star.
• Most stars are what we consider main
sequence (including our sun). They make up
90% of the stars in our sky. These stars are
the diagonal strip running through the
middle of the chart.
Why is it so important?
• This diagram is the single
most important that
astronomers use today.
• In the early 1900’s Ejnar
Hertzsprung (Danish) and
Henry Norris Russell
(American) found a
relationship between
the absolute magnitude
and the surface
temperature. The men
were working
independently.
• Hertzsprung presented
his information in 1905 in
the form of tables, while
Russell presented his
observations in table form
in 1913.
• Today the diagram is
named for both men’s
work in correlating a
star’s brightness and
surface temperature.
Absolute Magnitude
• Absolute Magnitude is the star’s actual
brightness. Apparent Magnitude is how bright a
star appears from Earth. The H-R Diagram is
based on the actual brightness of a star.
• If we place two stars were the same distance
from the Earth, and measured their brightness,
this would be their absolute magnitude.
Surface Temperature
• Astronomers use color as a guide to
determine the temperature.
• The hottest star is 50,000 °C
• The coolest star is around 3,000
°C
• Remember the Surface
Temperature is less here than the
core of the star.
So now what?
• The stars are plotted on the diagram
according to their surface temperature and
absolute magnitude.
• Once the stars are placed on the diagram,
astronomers have noticed clustering of the
plotted stars.
• These clusters are grouped together into
the various stages of a stars life cycle.
• Let’s look at those briefly.
Main Sequence Stars
The Sun
• Make up 90% of the stars
• These are medium sized
stars
• Our sun is a main
sequence star
• Sizes vary from 1/10 that
of our Sun to 10 times
that of our Sun
• Stars stay in this part of
their life cycle for a long
time; most of their “lives”
Giant Stars
• These stars are the next size up from the
Main Sequence stars
• They are 10-100 times as large as our Sun
Super Giants
• The largest stars, larger
than the giant stars
• Their diameters are 1,000
times that of our Sun
• A star this size would
extend past Mars from
where our Sun is now if
compared to our Sun’s
current size
• Due to their size, they are
the shortest lived stars
and die off quickly
White Dwarfs
• These are smaller than the sun and even
the Earth
• The smallest know white dwarf has a
diameter that is less then the distance
across Asia
Neutron Stars
• These are the smallest stars
• A typical neutron star is 16 km in diameter
Parallax
• Now using the parallax
activity we will
demonstrate the concept
of parallax, which is the
apparent change of a
stars position in the sky.
• The stars are not really
moving, rather the Earth
is and therefore we see
different constellations
during different seasons.
• This is used to measure a
stars distance from Earth
as well.
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