Stars in our
Universe
January 2013
• Definition: a large sphere of plasma held together by
gravity
• Compared to our closest star, the Sun:
• Some are very large, some are very small
• Some are very hot, some are “cold”
What are stars?
• An observed pattern of stars in the sky
• They represent mythical characters, animals, or familiar
objects
• Even though the stars look close together, they are really
light years apart!
Constellations
• Positioned almost directly over the North Pole
• All of the constellations in the Northern hemisphere
revolve around it
• Think of Polaris as the point of Earth’s axis
• The movement of the other constellations around Polaris
show that the Earth is rotating.
Polaris: The North Star
Absolute Magnitude
How bright the star is
FOR REAL
As in, if you were right
next to it, this is how
bright it would be
Apparent Magnitude
How bright the star
looks like from Earth
It may be bright to our
eyes, but FOR REAL, it
may not be as bright as
the one further away…
Absolute & Apparent
Magnitudes
• Color: indicates the temperature
• Red Color = cooler
• Blue/White Color = hotter
Think back to the spectrum:
• Red waves are safer and so are cooler temperatures
• Blue waves are damaging and so are hotter temperatures
Properties of Stars
• Acts like a prism and spreads the light out into colors
• Each dark line on the spectrum tells you what element is
in the star
• Stars can have more than one element in them
Spectroscope
• Cut out your elements from your spectral data of given
elements.
• These are the patterns for a specific element – like a fingerprint
• Do NOT cut out the stars from the second page
• Line up the spectral data with the star. If EVERY line matches
up – your star has that element.
• On the star data, circle the elements that are in each star.
Note: Even if 1 line does not match up – it does not have that
element. It must fit perfectly.
Spectral Data - Lab
1. What elements are found in all 5 stars?
2. Why do you think these elements are found in all 5
stars? (Think about where they are on the Periodic
Table)
3. Do any of the stars have all 8 elements?
4. What type of instrument do scientists use to collect star
spectral data?
Questions on worksheet