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Astronomy

Astronomy. - the study of stars. Stars. Huge spheres of hot, glowing gas Example = sun Stars give off energy---how do we know this?. Energy = waves Electromagnetic spectrum. Huge spheres of hot, glowing gas Example = sun Stars give off energy---how do we know this?

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Astronomy

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  1. Astronomy -the study of stars

  2. Stars • Huge spheres of hot, glowing gas • Example = sun • Stars give off energy---how do we know this?

  3. Energy = wavesElectromagnetic spectrum

  4. Huge spheres of hot, glowing gas • Example = sun • Stars give off energy---how do we know this? • Visible light = we can see lots of stars in the sky • Radiant energy from the sun heats the earth • Also, some stars give off radio waves

  5. Both of these are visible light telescopes Telescopes • Use lenses or mirrors to collect and focus light from distant objects • Three different types: • Refracting telescope • Reflecting telescope • Radio telescope

  6. Refracting telescope • Consists of 2 convex lenses • First lens (objective lens) gathers the light and focuses it • Second lens (eyepiece lens) magnifies it

  7. Reflecting Telescope • Uses a concave mirror to gather and focus light • A smaller mirror inside reflects this image to the eyepiece lens which magnifies it

  8. Radio Telescope • Detects radio waves given off by objects in space • Most have curved reflecting surfaces that are several hundred meters in diameter • The bigger the radio telescope, the more radio waves it can collect

  9. Telescopes: Similarities and Differences Traits which are only true of reflecting telescopes Traits which are only true of refracting telescopes Traits which are only true of radio telescopes

  10. Spectroscopes • Also called a spectrograph • Breaks the light from an object into its color spectrum • Astronomers use this to get information about stars including their chemical compositions and temperatures

  11. Spectroscopes: star’s chemical composition • What elements is a star made up of? • Astronomers compare the banding patterns of known elements to those of the stars.

  12. What elements does this star contain?

  13. What makes up the universe? • On the right side of your paper, list as many things as you can come up with in one minute. • Stars, galaxies, star systems, nebulae, etc. • Universe = space and everything in it!

  14. Review: What is a star? • A star is a huge sphere of hot, glowing gas. • Can you think of any examples of stars? • The sun is a star!

  15. Stars • What pieces of equipment can be used to gain information about stars? • Reflecting telescope • Refracting telescope • Radio telescope • SPECTROSCOPE!!

  16. What is a galaxy? • A galaxy is a cluster of stars. • Billions of stars make up a galaxy. Can you think of the name of our galaxy? • Milky Way galaxy

  17. How do we measure distance to stars and other galaxies? • We have to use a unit called a light year. • A light year is the distance light can travel in one year….HUGE! • light year is a unit of distance, not time!!!! • 1 light year= ~9.5 million million kilometers

  18. Parallax • Parallax is the apparent change in position of an object when you look at it from different places.

  19. What characteristics classify stars? • All stars are huge spheres of glowing gas (mostly hydrogen). • Stars are classified based on 3 main physical characteristics: • Temperature • Brightness • size

  20. LAB: Color vs. Temperature • You will record the data for your lab in your Cornell notes on the RIGHT side.

  21. Summary of Lab Findings • On the right side, place the order of star color by increasing temperature For example: Coolest colornext colordsfsjsdhfjkhottest color

  22. Temperature of stars • Color of a star reveals its temperature. • Remember the color vs. temperature lab? • Red stars = relatively cool stars (still hot ~3200 degrees Celsius) • Yellow- white = medium temperature (~5500 degrees Celsius) • Blue-white stars= hottest stars (>10,000 degrees Celsius)

  23. Brightness of stars • Brightness = the amount of light stars give off • This depends on its size and temperature • How bright it looks from Earth depends on distance and actual brightness • Apparent magnitude • Absolute magnitude

  24. Apparent Magnitude • Brightness as seen from Earth • Example: the sun looks very bright to us on Earth, but it is not the brightest star • It looks brighter because it is closer to earth than other stars.

  25. Absolute Magnitude • Brightness of a star if it were a standard distance from the earth

  26. Review • What characteristics are used to classify stars? • Now, we will look at graphs that show these characteristics of stars…they are called HR diagrams

  27. Hertzsprung – Russell Diagram

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