2. UNIT NINE: Matter and Motion in the Universe  Chapter 26 The Solar System  Chapter 27 Stars  Chapter 28 Exploring the Universe

4. Chapter Twenty-Eight: Exploring the Universe  28.1 Tools of Astronomers  28.2 Galaxies  28.3 Theories about the Universe

5. 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.

6. Investigation 28A  Key Question: How does a telescope work? Tools of Astronomy

7. 28.1 Tools of Astronomers  The universe is defined as everything that exists, including all matter and energy.

8. 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?

10. 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.

11. 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 × 10 12 km  1 pc = 3.26 ly  Solution:  10 pc (3.26 ly) x (9.46 x 10 12 km) = 3.08 x 10 13 km 1 pc 1 ly Solving Problems

12. 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.

13. 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.

14. 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.

15. 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 Solving Problems

16. 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.

17. 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.

18. 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.

19. 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.

20. 28.1 Telescopes and electromagnetic waves  Astronomers use different types of telescopes to view the different types of waves emitted by objects in space. 1.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. 3.X-ray telescopes are designed to detect high-energy radiation (X-rays) from space.

21. 28.1 Telescopes and electromagnetic waves  These images of the Crab Nebula were taken with different telescopes.  Each new view gave astronomers more information.

22. 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.

23. 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.

24. 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.

25. 28.1 Spacecraft  In April 1961, Yuri Gagarin of the former Soviet Union was the first human to travel in space.

26. 28.1 Spacecraft  Alan Sheppard of the U.S. followed on May 5.

27. 28.1 Spacecraft  This led to the NASA Manned Lunar Program known as Apollo, which lasted from 1963 to 1972.

28. 28.1 Spacecraft  Space shuttles are piloted spacecraft that launch from rocket “boosters” and can land back on Earth like an airplane.

29. 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.

30. 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 Earth’s surface.  On board, scientists conduct numerous experiments, many of which depend on the constant free fall (microgravity).

31. 28.1 Spacecraft  NASA’s 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

32. 28.1 Spacecraft  NASA’s 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.