Laws of Motion and Energy

1
(No Transcript)
2
Laws of Motion and Energy
3
Chapter Seven Gravity and Space

• 7.1 Gravity
• 7.2 The Solar System
• 7.3 The Sun and the Stars

4
Investigation 7B
The Sizes of the Solar System

• How big is the solar system?

5
7.3 Stars

• A star is essentially an enormous, hot ball of
  gas held together by gravity.
• The density at the suns core is about 158.0
  g/cm3.

This is about 18 times the density of solid
copper!
6
7.3 Why stars shine

• At high density and pressure, nuclear fusion
  occurs, releasing tremendous amounts of energy.
• Fusion reactions in the sun combine hydrogen to
  make helium.

7
7.3 Anatomy of the sun

• The corona is the outermost layer of the suns
  atmosphere, extending millions of kilometers
  beyond the sun.
• Sunspots are areas of gas that are cooler than
  the gases around them.

8
(No Transcript)
9
7.3 Types of stars

• Stars come in a range of sizes and temperatures.
• Blue giant stars are hot and much more massive
  than the sun.
• Stars that are smaller than the sun come in two
  main categories, dwarfs and neutron stars.

10
7.3 Distances to the nearest stars

• One light year is the distance that light travels
  through space in one year.
• A light year is a unit of distance, not time.

11
7.3 Temperature and color

• If you look closely at the stars on a clear
  night, you might see a slight reddish or bluish
  tint to some stars.
• This is because stars surface temperatures are
  different.

12
(No Transcript)
13
7.3 Temperature and color

• Red stars are cooler than white stars, and blue
  stars are the hottest.
• White light is a mixture of all colors at equal
  brightness.

14
7.3 Galaxies

• A galaxy is a huge group of stars, dust, gas, and
  other objects bound together by gravitational
  forces.
• The sun, along with an estimated 200 billion
  other stars, belongs to the Milky Way galaxy.

15
7.3 Galaxies

• The disk of the Milky Way is a flattened,
  rotating system that contains young to
  middle-aged stars, along with gas and dust.

16
7.3 Distances between galaxies

• The distances between stars are 10,000 times
  greater than the distances between planets.
• The distances between galaxies are a million
  times greater than the distances between stars.

17
7.3 Distances between galaxies

• Figuring out the distance between galaxies is one
  of the more difficult tasks in astronomy.
• A faint object in the night sky could be a dim
  object that is relatively nearby or a bright
  object that is far, far away.

18
7.3 Distances between galaxies

• The most reliable method for estimating the
  distance to a galaxy is to find a star whose
  luminosity is known.
• If the luminosity is known, the inverse square
  law can be used to find the distance from the
  observed brightness.

19
Astronomy Connection
Extraterrestrial Volcanoes

• There are active volcanoes on Earth, but did you
  know that a moon of Jupiter is considered the
  most volcanically active place in the solar
  system?

20
Activity
Sunspots

• Sunspots are large, dark regions that appear on
  the surface of the Sun.
• In this activity, you will determine the diameter
  of the Sun and the number of sunspots on the Sun.