Unit 1 The Universe

1. Unit 1 The Universe Mrs. Morgan 8th Grade

2. Big Idea: • The sun is one of billions of stars in one of billions of galaxies in the universe.

3. Unit 1 Lesson 1 Structure of the Universe Our Place in Space • Universe-space & all the matter &energy in it. • Galaxy- a large collection of stars, gas, & dust • There are an estimated 100 billion galaxies in the universe. Milky waygalaxy Earth Universe Solar system

4. Unit 1 Lesson 1 Structure of the Universe Types of Galaxies • Spiral galaxies are shaped like pinwheels. They have a central bulge from which two or more spiral arms extend. • Elliptical galaxies look like spheres or ovals and do not have spiral arms. • Irregular galaxies appear as splotchy, irregularly shaped “blobs.” They are very active areas of star formation. http://library.thinkquest.org/C0110277/images/galaxies.gif

5. Unit 1 Lesson 1 Structure of the Universe What Makes Up the Universe? • Solar system- the collection of large & small bodies that orbit our central star, the sun. • Planet-spherical body that orbits the sun.

6. Unit 1 Lesson 1 Structure of the Universe TerrestrialPlanets • Terrestrial Planets- rocky, dense, and relatively small. • Mercury, Venus, Earth and Mars http://ut-images.s3.amazonaws.com/wp-content/uploads/2008/04/mercurycomparison.jpg

7. Unit 1 Lesson 1 Structure of the Universe • Gas giant planets - have thick, gaseous atmospheres; small, rocky cores; and ring systems of ice, rock, and dust. • Jupiter, Saturn, Uranus, and Neptune.

8. Unit 1 Lesson 1 Structure of the Universe Small Bodies in the Universe • Moons- orbit most of the planets. Earth has only one moon, but Jupiter has more than 60. • The solar system has other small bodies, including • Dwarf planets • Comets • Asteroids • Meteoroids • http://home.earthlink.net/~meshellwg/w/www/images/comet.jpg

9. Unit 1 Lesson 1 Structure of the Universe Measuring the Universe • Distances between most objects in the universe are so large that astronomers measure distances using the speed of light. • Light-year -the distance that light travels through space in one year. • Light travels through space at about 300,000 km/s, or about 9.5 trillion kilometers in one year.

10. Unit 1 Lesson 1 Structure of the Universe Reach For The Stars! • Star - large celestial body that is composed of gas & emits light. • Most stars are composed almost entirely of hydrogen and helium. • Stars emit light and vary in brightness, size and temperatures. http://www.le.ac.uk/ph/faulkes/web/images/stars.jpg

11. Unit 1 Lesson 2 Stars You’re a Shining StarHow is star brightness measured? • Apparent magnitude-measure of a star’s brightness as seen from Earth. • Luminosity- actual brightness of a star. • Absolute magnitude-measure of how bright a star would be if the star were located at a standard distance.

12. Unit 1 Lesson 2 Stars Too HOT to Handle • Surface temperatures of Stars are measured by their COLOR

13. Unit 1 Lesson 2 Stars Stars differ greatly in size • White dwarfs - Very small stars have about the same radius as Earth, which is approximately 0.01 solar radius. • Giant stars - Very large stars, typically have sizes between 10 and 100 times the sun’s radius. • Supergiants - Some rare, extremely large stars have sizes of up to 1,000 solar radii.

14. Unit 1 Lesson 3 The Life Cycle of Stars A Star Is Born What is the life cycle of a star? • Stars form in nebulae. • Nebula -large cloud of gas and dust. It is composed mainly of hydrogen and helium, with small amounts of heavier elements. http://dsc.discovery.com/convergence/hubble/hits/gallery/garden4_lrg.jpg

15. Unit 1 Lesson 3 The Life Cycle of Stars • Birth of a Star • Nuclear fusion–high temp & pressure cause two or more low-mass atomic nuclei to form a heavier nucleus.

16. Unit 1 Lesson 3 The Life Cycle of Stars The Lightweights • Low-mass stars • Giants-large red stars due to star’s outer atmosphere expanding after active fusion ends. • White dwarf -hot, dense core of matter that remains from the collapse of a low-mass star. It is about the size of Earth.

17. Unit 1 Lesson 3 The Life Cycle of Stars The Heavyweights • High mass stars • Supergiant-produces heavier elements like carbon • Supernova -gigantic explosion in which a high-mass star collapses, throwing its outer layers into space. But its core remains. • Neutron star-small, incredibly dense ball of closely packed neutrons. • Black hole -invisible object with gravity so great that nothing, not even light, can escape it.

18. Unit 1 Lesson 3 The Life Cycle of Stars A Graphic Display • H-R diagram-illustrates this pattern is called the Hertzsprung-Russell diagram, or. • Main sequence -region of the diagram where stars spend most of their lives.