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DO NOW: Write it down 

DO NOW: Write it down . 1. Most of the galaxies in the universe are moving __________ from us. 2. Our evidence to support this is ___ ___________________________. 3. One exception to this is the galaxy ______________ which is moving toward us (it has a ___________). 4. Why?.

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DO NOW: Write it down 

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  1. DO NOW:Write it down  1. Most of the galaxies in the universe are moving __________ from us. 2. Our evidence to support this is ___ ___________________________. 3. One exception to this is the galaxy ______________ which is moving toward us (it has a ___________). 4. Why?

  2. AIM: How can we characterize stars? Constellations: groups of stars * Human invented Apparent movement caused by Earth’s rotation and revolution Because Earth rotates from WEST to EAST, the sky seems rotate counter clockwise around Polaris! *Sun moon and stars rise in East and set in West. Polaris is stationaryhttp://www.skyviewcafe.com/skyview.php

  3. Why does the sky change? • The sky SEEMS to change * NIGHTLY- because of Earth’s ROTATION (spin on axis)- 15°/hr *SEASONALLY- because of Earth’s REVOLUTION (orbit around sun) 360° around slightly elliptical orbit in 365 days. http://www.classzone.com/books/earth_science/terc/content/visualizations/es0408/es0408page01.cfm

  4. Rotation Seasonal Changes Nightly Changes

  5. ApparentMagnitude- How bright a star seems to be to an observer on Earth * DEPENDS ON HOW CLOSE A STAR IS TO EARTH Our next closest star, Proxima Centuri Our Sun VS.

  6. Luminosity- a star’s ACTUAL brightness. It depends on the size and temperature. *DISTANCE FROM EARTH IS NOT A FACTOR! Absolute magnitude- measure of how bright stars would be if they were the same distance from Earth Example) What if I held a light bulb in front of your face and then walked across Port Blvd? Would it look the same size? Would it still BE the same size?

  7. Astronomical Unit- the distance from Earth to closest star (sun) 150 million km. Proxima Centuri is the next closest star (260,000 AU)

  8. FORCES that balance out a star- 1. Nuclear fusion- 1 Hydrogen + 1 Hydrogen = Heliumhttp://www.astronomynotes.com/starsun/s3.htm Pushes outward 2. Gravity – pulls inward

  9. HR DIAGRAM aka stars’ family album Have you seen any of these? • http://aspire.cosmic-ray.org/Labs/OldStarLife/hr_interactive.html (Open links in internet Explorer) http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa/stars/planetsstarsandgalaxiesact.shtml

  10. ~DENEB~ • Now even though it is a massive super-giant, Deneb is actually a very young star, at least compared to the sun. • Deneb was born only about 3 million years ago, long after the Dinosaurs died out, and is already approaching the end of its life -- the star can last at most another million years. • Compare this to the life of our sun -- it has been around for 5 BILLION years, and has another 5 billion left in it. This is because Deneb is so much more massive than the sun. • The greater mass causes greater pressure and forces the star to burn much hotter (shorter wavelength) and faster. With stars, the bigger they are, the harder they fall. NOTE- Deneb is 2,600 light –years away. http://my.execpc.com/60/B3/culp/astronomy/Fall/MilkyWay.html

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