Astronomy Day 7: How stars form

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Astronomy Day 7How stars form

• Goal
• Demonstrate your understanding of the Big Bang
  Theory, Galaxies, and Gravity.
• Explain the connection between the force of
  gravity and the formation of stars.

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Bellringer

• Explain one key concept that you already
  understand about
• The Big Bang Theory
• Gravity
• Galaxies
• What questions remain related to
• The Big Bang Theory
• Gravity
• Galaxies

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Common Misconceptions

• Gravity only affects large objects.
• FALSE. The tiniest particles in the universe
  have gravitational attraction for other
  particles. If an object has any mass at allno
  matter how smallit has gravitational attraction.
  Remember the equation!
• Gravity only goes one way.
• FALSE. Gravitational attraction is between two
  objects. For example, you know that the Earth
  pulls on you, but you pull just as hard on the
  Earth. Your weight is a measure of the force of
  attraction of the Earth for you and you for the
  Earth

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Common Misconceptions

• Gravity is a powerful force.
• Actually, of all the natural forces in the
  universe, gravity is the weakest by far. The
  forces that holds the nucleus of atoms together
  are much, much more powerful. The only reason we
  tend to think of it as powerful is because we are
  gravitationally attracted to a very massive
  objectEarth.

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Common Misconceptions

• Astronauts in space are weightless.
• This is absolutely FALSE. The space shuttle
  would not orbit the Earth unless gravity were
  acting on it. The only reason astronauts in the
  shuttle appear weightless is because they are
  falling around the Earthjust like a skydiver
  appears weightless when he/she is falling toward
  the earth.

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Common Misconceptions

• You can escape gravity.
• This one is a little tricky. Technically, you
  can never escape an objects gravitylike the
  Earth. Millions of miles from the Earth there is
  still a small amount of gravity.
• There is a thing called escape speed, but this is
  not how fast you have to go to escape an objects
  gravity. It is how fast you have to travel to
  not fall back toward the object, or be pulled
  into orbit around it.

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Quiz Time!

• Quickly, do you have any questions about the Big
  Bang Theory or Gravity?

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When you finish

• Text cha-cha (if it doesnt cost you money) and
  find out your astrological sign, if you dont
  already know it.
• Explain the connetion between the force of
  gravity and the formation of stars. You may use
  a textbook if necessary.

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Constellation Demonstration

• Why do we see different constellations in the
  night sky at different times of the year?
• Where would constellations that we can see all
  year long in the night sky be located in our
  demonstration?
• How does your position on the Earth affect what
  constellations you see in the night sky?
• What is your astrological sign based on? Is it a
  constellation that is visible in the night sky
  when you were born, or is it something else?

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Summer and winter constellations are different
because

• Of the spin of the Earth about its polar axis
• The night sky faces in opposite directions in
  summer and winter
• Of the tilt of the Earths polar axis
• The Earth is at solar perigee in winter and
  apogee in summer
• The universe is symmetric and harmonious

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We do not see stars in the daytime because

• The sun blocks their view
• They simply dont exist in the daytime part of
  the sky
• Skylight overwhelms the starlight
• Of the lack of contrast with moonlight
• The solar wind obscures their view.

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What could be happening here?
Which came firstgalaxies or stars?
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Forces in the Life of a Star

• Outward push of radiation pressure and fusion
• Inward crush of a stars massive gravity

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(No Transcript)
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Star Formation

• New stars form in nebula
• Gravity pulls matter together and the temperature
  increaseshot dense object called a prostar
• When the temperature in the core reaches 10
  million K, fusion beginsa star is born

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Larger Stars vs. Smaller Stars
What does that have to do with dogs?
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Ticket Out

• Explain the connection between gravity and the
  formation of stars