GALAXIES

1. GALAXIES These are galaxy clusters and separate galaxies taken by long-range telescope. The area of the sky covered is less than the diameter of the moon.

2. DISTANCE IN THE UNIVERSE • Light year: ______________________________________ • ________________________________________________ • Light moves at a velocity of about 180,000 miles each second (300,000 km each second). One light year is equal to 5,880,000,000,000 miles • Milky Way Galaxy is about 150,000 light-years across. • Andromeda Galaxy (one of our nearest neighboring galaxies) is 2.3 million light-years away. • Center of the galaxy is approximately 30,000 light years away. Unit of distance (NOT TIME). It is the distance that light travels in one year.

3. distance light travels in a vacuum in one minute. • Light minute – ________________________________________ • Sun is approximately 8.3 light-minutes away • Light second – _________________________________________ • Moon is approximately 1.3 light-seconds away. distance light travels in a vacuum in one second Astronomical Unit: _________________________________ ___________________________________________________ It is approximately 93 million miles. Mercury is about 1/3 of an AU from the Sun. It is not big enough when we talk about anything outside of our solar system. Average distance between the Earth and the Sun.

4. Billions of stars, dust, and gas held together by gravity Galaxies: _____________________ _____________________________ ______________________________ Edwin Hubble ________________ was an astronomer in the 1920s who gathered many pictures of galaxies • noticed they all didn’t look alike • decided to classify them by the way they looked into 3 types • “E” or _____________________ • “S” or _____________________ • “SB” or ____________________ Elliptical Spiral Barred Spiral

5. HUBBLE TUNING FORK DIAGRAM http://cse.ssl.berkeley.edu/SegwayEd/lessons/classifying_galaxies/answers.htm

6. 3 types of galaxies wasn’t enough, so Hubble furthered divided the galaxies by variations within each galaxy type • For “E” or ____________________ he looked at the amount of flattening (elongation/roundness) • Divided into E0 to E5 Elliptical Spiral • For “S” or ____________________ he looked at how tightly the arms were wound around the bright center • Divided into Sa, Sb, or Sc Barred Spiral • For “Sb” or ____________________ he looked at the increased openness of the arms (spiral arms) • Divided into SBa, SBb, or SBc

7. Elliptical: • __________________________; • have an elliptical shape that ranges to nearly spherical, and lack spiral arms most abundant type http://spitzer.as.utexas.edu/~twitch/M87.jpg http://zebu.uoregon.edu/~soper/ImGalaxies/m95.gif

8. Spiral: • typically disk-shaped; • Somewhat greater concentration of stars near their centers, often containing _________________ • __________________________. arms of extending from their central nucleus http://cse.ssl.berkeley.edu/bmendez/pics/TRGB/NGC2903.jpg http://www.nrc-cnrc.gc.ca/education/images/cdnskies/photos/spiral-galaxy.jpg

9. Barred Spiral: • type of spiral galaxy • Has the stars arranged in the__________________, which rotates as a rigid system shape of a bar http://www.mindspring.com/~dhanon/ngc7479.jpg http://nrumiano.free.fr/Images_gx/NGC1365.jpg

10. 4. Irregular: • lack symmetry • account for only 10 percent of known galaxies http://starchild.gsfc.nasa.gov/Images/StarChild/universe_level2/ngc6822.gif http://library.thinkquest.org/3461/media/irreg_2.jpg http://www.astro.psu.edu/users/stark/ASTRO11/lab11-12images/irregular/aat064.jpg

11. The Milky Way: Sun __________is only one of 200 billion stars in the Milky Way It is a large, disk-shaped, ______________________ about 100,000 light-years wide and about 10,000 light-years thick at the center (central bulge) There are 3 distinct spiral arms of stars spiral galaxy

12. The sun is positioned on one of these arms about 2/3 of the way from the galactic center, at a distance of 30,000 light-years. Scientist suspect there is a super massive ______________ at the center of the galaxy It takes over 200 million years for the sun to revolve around thegalactic center. black hole

13. II. The Expanding Universe A. The Big Bang Theory: ____________________________ ________________________________________________ ________________________________________________ Idea that all matter began in an infinitely small point and exploded out in all directions

14. http://www.tech.purdue.edu/Cgt/Courses/cgt211/private/images/projects/archive/3-SciVis/F02/Big-Bang--final.jpghttp://www.tech.purdue.edu/Cgt/Courses/cgt211/private/images/projects/archive/3-SciVis/F02/Big-Bang--final.jpg

15. B. Doppler Shift 1. red shift: ______________________________________ _________________________________________________ 2. blue shift: _____________________________________ ____________________________________________________ Galaxies moving away from us should show a shift in their spectrum toward the red end Galaxies moving toward us should show a shift toward the blue end of the spectrum

16. Since the spectrum for all galaxies show a ________________ from Earth, we assume the universe is ___________________ Red shift expanding http://library.thinkquest.org/19537/java/Doppler.html