1. Astronomy
Big Idea: The sun is one of billions of stars in one of billions of galaxies in the universe.

2. Observing the Universe
EQ: What can we learn from space images?

3. Astronomy - the study of stars
What characteristics might we learn about when we are studying astronomy (or the stars)?

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

5. 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

6. Energy = waves Electromagnetic spectrum all of the frequencies or wavelengths of electromagnetic radiation

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

8. Refracting telescope
Uses lenses to gather and focus light

9. Reflecting Telescope
Uses mirrors to gather and focus light

10. 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

11. 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, temperatures, and motion

12. 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.

14. What elements does this star contain?

15. Temperature of stars Color of a star reveals its temperature.
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)

16. The temperature and composition of stars

17. Doppler Effect
The Doppler effect says that things moving away from you look redder than they would if they weren’t moving. Things moving towards you look more blue.

18. Doppler Effect The change in wavelength of a moving object
Red Shift – objects moving away from observer
Blue Shift – objects moving toward observer

19. 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