UNIT NINE: Matter and Motion in the Universe

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UNIT NINE Matter and Motionin the Universe

• Chapter 26 The Solar System
• Chapter 27 Stars
• Chapter 28 Exploring the Universe

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Chapter Twenty-EightExploring the Universe

• 28.1 Tools of Astronomers
• 28.2 Galaxies
• 28.3 Theories about the Universe

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Section 28.1 Learning Goals

• Apply formulas to solve astronomy problems.
• Discuss the significance of the Hubble Space
  Telescope.
• Compare and contrast reflecting and refracting
  telescopes.

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Investigation 28A
Tools of Astronomy

• Key Question
• How does a telescope work?

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28.1 Tools of Astronomers

• The universe is defined as everything that
  exists, including all matter and energy.

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28.1 Astronomical numbers

• Scientific notation is a mathematical
  abbreviation for writing very large (or very
  small) numbers.

How do scientists write the number 150,000,000?
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28.1 Astronomical distances

• Astronomers have developed units other than
  kilometers or meters to measure the vast
  distances in space.
• One light year is equal to the distance that
  light travels through space in one year.

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Solving Problems

• How far is 10 parsecs in kilometers?
• Use scientific notation in your answer.
• Looking for
• distance in km
• Given
• distance 10 pc
• Relationships
• 1 ly 9.46 1012 km
• 1 pc 3.26 ly
• Solution
• 10 pc (3.26 ly) x (9.46 x 1012 km) 3.08 x 1013
  km
• 1 pc 1 ly

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28.1 Determining distances to closer objects in
the universe

• Astronomers use a method called parallax to
  determine the distance of stars that are closer
  than 1,000 light years to Earth.
• As Earth revolves around the Sun, the nearby
  stars appear to change positions in the sky over
  the course of one year.

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28.1 Determining distances to closer objects in
the universe

• To use parallax, astronomers determine the
  position of a closer star (moving) in relation to
  faraway stars (not moving).
• Next, they look at the same star six months
  later, and measure its change in position
  relative to the distant stars.

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28.1 Studying the universe

• Light from other galaxies and stars takes time to
  reach Earth.
• The farther away the object they are viewing, the
  further back in time astronomers are looking.

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Solving Problems

• How long does it take for radio waves to travel
  from the Moon to Earth?
• Looking for
• Time in seconds (s)
• Given
• distance from Earth to Moon 384,400 km
• speed of light 300,000 km/s
• Relationships
• Speed distance time (rearrange variables)
• Time distance speed
• Solution
• 384,400 km 300,000 km/s 1.28 s

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28.1 Telescopes

• A telescope is a device that makes objects that
  are far away appear closer.
• In the 1600s, Galileo was the first to use a
  telescope for viewing the night sky.

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28.1 Telescopes

• Telescopes work by collecting the light from a
  distant object with a lens or mirror and bringing
  that light into a concentrated point, called the
  focal point.

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28.1 Telescopes

• A refracting telescope uses lenses to bend, or
  refract, light, making objects look bigger.
• Refracting telescopes are made from a long tube,
  a glass objective lens that you point toward the
  sky, and an eyepiece lens.

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28.1 Telescopes

• A reflecting telescope uses mirrors instead of
  lenses to gather and focus light.
• A concave mirror (called the primary mirror) is
  placed at the back of a tube.
• The secondary mirror deflects the light to an
  eyepiece lens.

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28.1 Telescopes and electromagnetic waves

• Astronomers use different types of telescopes to
  view the different types of waves emitted by
  objects in space.
• A radio telescope works like an extremely
  powerful receiver that picks up radio waves from
  space.
• Infrared telescopes are often placed on
  satellites that orbit above Earth.
• X-ray telescopes are designed to detect
  high-energy radiation (X-rays) from space.

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28.1 Telescopes and electromagnetic waves

• These images of the Crab Nebula were taken with
  different telescopes.

• Each new view gave astronomers more information.

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28.1 Satellites and other space craft

• The Moon is a natural satellite that orbits
  Earth.
• On October 4, 1957, the former Soviet Union
  launched Sputnik I, the first artificial
  satellite to orbit Earth.

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28.1 Satellites and other space craft

• The Hubble Space Telescope is a satellite that
  orbits Earth out of reach of light pollution.
• It sends images from deep space to computers back
  on Earth.

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28.1 Spacecraft

• Space probes are unmanned spacecraft that carry
  scientific instruments on board.
• Launched in 1977, the NASA Voyager 1 and 2 probes
  are still sending information back to Earth via
  radio waves.

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28.1 Spacecraft

• In April 1961, Yuri Gagarin of the former Soviet
  Union was the first human to travel in space.

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28.1 Spacecraft

• Alan Sheppard of the U.S. followed on May 5.

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28.1 Spacecraft

• This led to the NASA Manned Lunar Program known
  as Apollo, which lasted from 1963 to 1972.

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28.1 Spacecraft

• Space shuttles are piloted spacecraft that launch
  from rocket boosters and can land back on Earth
  like an airplane.

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28.1 Spacecraft

• Developed by NASA, space shuttles are used to
  conduct experiments in space, to launch and
  repair satellites, and to transport people to and
  from space stations.

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28.1 Spacecraft

• The International Space Station is a joint effort
  of many countries in Europe, Asia and North and
  South America.
• It orbits about 400 kilometers above Earths
  surface.
• On board, scientists conduct numerous
  experiments, many of which depend on the constant
  free fall (microgravity).

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28.1 Spacecraft

• NASAs Mars Exploration Rover (MER) Mission began
  in 2003.
• Two unmanned rovers, Spirit and Opportunity, were
  sent to explore the surface features and geology
  of Mars.

Two generations of Mars Rovers Sojourner and
Spirit
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28.1 Spacecraft

• NASAs Phoenix lander launched in August 2007.
• The lander contains a robotic arm that digs
  through the Martian soil and brings samples
  onboard for scientific analysis.