Stars

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Stars
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What is a star?
- body of gasses that give off tons of energy
(light heat)
- clusters those little specks in the sky that
we see may really be more than one star.
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Star patterns

• 1000s of years of observations - want to
  organize what they saw

• constellations they are named after animals,
  greek gods and legendary heroes
• there are 88 named constellations

There are sub-groups within a constellation
asterisms (ex/ Big Dipper)
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The stars of a constellation only appear to be
close to one another Usually, this is only a
projection effect. The stars of a constellation
may be located at very different distances from
us.
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APPARENT Magnitude

• the brightness how WE see it
• the brightest star in a constellation is called
  the alpha, then beta, etc Greek letter (a,
  ß, ?)

Size and closeness can effect apparent magnitude
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Orion
Betelgeuse a OrionisRigel b Orionis
Betelgeuse
Rigel
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What should be the brightest star for us?

• THE SUN!
• its the closest - so it should appear the
  brightest

• BUT - its just average in reality
• ABSOLUTE magnitude real brightness

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Star Color

• if you look close enoughyoull see colors.
• blue HOT 20,000o - 50,000o
• red not so hot 3000o

Our sun yellow/orange 6,300o
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• Every element has its own characteristic color
  when made to emit light.
• The light from glowing elements can be analyzed
  with a Spectroscope

Spectrum
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Stars on the move

• high powered telescopes can see ACTUAL motion,
  but from here we only see the APPARENT motion

What causes APPARENT MOTION?

• caused by Earths rotation!
• creates the ecliptic path of the sun

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Polaris (North Star)
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Stellar Parallax
Parallax shift in angle that occurs when a
nearby object is seen against a distant backdrop
from two different perspectives
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Viewed from these two different locations, a
nearby star would appear to shift position with
respect to more distant stars
The bigger the shift, the closer the star is to
earth
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