galaxies these are galaxy clusters and separate galaxies taken by long-range telescope. the area of...
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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.
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.
DISTANCE IN THE UNIVERSE
Unit of distance (NOT TIME). It is the distance that light travels in one year.
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.
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 minute.
distance light travels in a vacuum in one second
Average distance between the Earth and the Sun.
Galaxies: _____________________ ___________________________________________________________
Billions of stars, dust, and gas held together by gravity
________________ 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
Edwin Hubble
http://cse.ssl.berkeley.edu/SegwayEd/lessons/classifying_galaxies/answers.htm
HUBBLE TUNING FORK DIAGRAM
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
• For “S” or ____________________ he looked at how tightly the arms were wound around the bright center
•Divided into Sa, Sb, or Sc
• For “Sb” or ____________________ he looked at the increased openness of the arms (spiral arms)
•Divided into SBa, SBb, or SBc
Elliptical
Spiral
Barred Spiral
1.Elliptical: • __________________________; • have an elliptical shape that ranges to nearly spherical,
and lack spiral arms
http://zebu.uoregon.edu/~soper/ImGalaxies/m95.gif http://spitzer.as.utexas.edu/~twitch/M87.jpg
most abundant type
2.Spiral: • typically disk-shaped;• Somewhat greater concentration
of stars near their centers, often containing _________________
__________________________.
http://www.nrc-cnrc.gc.ca/education/images/cdnskies/photos/spiral-galaxy.jpg
http://cse.ssl.berkeley.edu/bmendez/pics/TRGB/NGC2903.jpg
arms of extending from their central nucleus
3.Barred Spiral: • type of spiral galaxy • Has the stars arranged in the__________________,
which rotates as a rigid system
http://nrumiano.free.fr/Images_gx/NGC1365.jpg
http://www.mindspring.com/~dhanon/ngc7479.jpg
shape of a bar
4. Irregular: • lack symmetry •account for only 10 percent of known galaxies
http://library.thinkquest.org/3461/media/irreg_2.jpg
http://starchild.gsfc.nasa.gov/Images/StarChild/universe_level2/ngc6822.gif
http://www.astro.psu.edu/users/stark/ASTRO11/lab11-12images/irregular/aat064.jpg
The Milky Way:
__________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
Sun
spiral galaxy
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 the galactic center.
black hole
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
http://www.tech.purdue.edu/Cgt/Courses/cgt211/private/images/projects/archive/3-SciVis/F02/Big-Bang--final.jpg
B. Doppler Shift1. 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
Since the spectrum for all galaxies show a ________________ from Earth, we assume the universe is ___________________
Red shiftexpanding
http://library.thinkquest.org/19537/java/Doppler.html