Characteristics of Stars Section 2

1. Chapter 21 Stars, Galaxies, and the Universe Characteristics of StarsSection 2 Image From: http://www.nasa.gov/

2. Characteristics of Stars • It takes light 8 minutes to travel from the sun to the Earth. • It would take 4.2 years for light to travel from the nearest star to the Earth. • The nearest star to the Earth is Proxima Centauri. • Intro- • duction

3. Characteristics of Stars • Our solar system is found in the Milky Way Galaxy. • A galaxy is a cluster of stars. • The Milky Way contains hundreds of billions of stars. • It would take you 25,000 years to travel to the center of our galaxy moving at the speed of light. • Intro- • duction

4. Characteristics of Stars • The nearest galaxy to the Milky Way is the Andromeda Galaxy. • It would take you 2 million years to get to this galaxy traveling at the speed of light. • There are billions of galaxies found in the universe. • The universe contains space and everything in it. • Most of the universe made up of empty space. • Intro- • duction

5. Characteristics of Stars • Light-years are used to measure large distances in space. • A light-year is the distance light travels in one year – 9.5 million million kilometers. • If it takes light 4.2 years to reach Earth from Proxima Centauri, how many light years away is it? - 4.2 light years • Distances to Stars

6. Characteristics of Stars • Astronomers use parallax to measure distances to nearby stars. • Parallax is the apparent change in position of an object when you look at it from different places. • Astronomers measure how much a star appears to move against a background of stars that are much farther away. • Measuring • Distances • to Stars

7. Characteristics of Stars • The movement of the star is called the parallax shift. • The less a star appears to move, the farther away it is. • We are only able to measure stars that are 1,000 light years away or less. • Measuring • Distances • to Stars

8. Characteristics of Stars Image From: www.phy.syr.edu

9. Characteristics of Stars • The main characteristics that are used to classify stars are . . . • size. • temperature. • brightness. • Classifying Stars

10. Characteristics of Stars • There are different sizes of stars in the sky. • Sizes listed from largest to smallest: • Supergiant Star • Giant Star • Medium-Sized Star • White Dwarf Star • Neutron Star • Our Sun is a medium-sized star. • Sizes of Stars

11. Characteristics of Stars Image From: www.sciencenewsforkids.org

12. Characteristics of Stars Image From: www.physics.uci.edu

13. Characteristics of Stars Image From: www.oglethorpe.edu

14. Characteristics of Stars • Stars have different colors. • A star’s color tells its temperatures. • Colors of stars from coldest to warmest: • Red ( 3,200 ºC ) • White ( 5,500 ºC ) • White -blue ( 10,000 ºC ) • Color • and • Temper-atures • of Stars

15. Characteristics of Stars Image From: www. williams.edu

16. Image From: www.nasaimages.org

17. Characteristics of Stars

18. Characteristics of Stars • Brightness of the star depends upon size and temperature. • How bright a star looks from Earth depends on both how far the star is from Earth and how bright the star is actually. • Brightness of Stars

19. Characteristics of Stars • Apparent magnitude is a star’s brightness as seen from Earth. • Absolute magnitude is the brightness a star would have if they were compared side-by-side. • Astronomers use the apparent magnitude and the star’s distance from the sun to find the absolute magnitude. • Brightness of Stars

20. Characteristics of Stars • The Hertzsprung-Russell diagram shows how the temperatures of stars relate to their brightness. • In the main sequence of the graph (most stars), as the temperature of the graph increases, so does the brightness. • The • Hertzsprung- • Russell • Diagram

21. Characteristics of Stars Image From: www.zoomschool.com

22. Characteristics of Stars Image From: www.lcogt.net