Telescopes & Light: Part 1

1. Telescopes & Light: Part 1

2. A Telescopes is a tool used to gather light from objects in the universe.

3. There are two different types of telescopes: • A refracting telescope uses a glass lens to concentrate incoming light. • A reflecting telescope uses mirrors to concentrate incoming starlight.

4. Which of the following is the most important feature of a telescope? • Ability to gather light. • Ability to see fine detail. • Ability to magnify the image.

5. Three main functions of a telescope • Most important!! • Gather More Light – (bigger Is better) making objects appear brighter • followed by • to see fine detail • (called resolution) • and least important, • magnify • magnification = (objective lens focal length / eyepiece lens focal length)

6. A larger objective lens provides a brighter (not bigger) image

7. If you pass white light through a prism, it separates into its component colors. long wavelengths ROY G B I V short wavelengths spectrum

8. But visible light is only one type of electromagnetic radiation (light) emitted by stars Astronomers are truly interested in the entire spectrum of light!

9. Consider Orion as Seen in Different Wavelengths of light!

10. Observations at other wavelengths are revealing previously invisible sights UV Infrared Map of Orion region Ordinary visible

11. Sun as seen in visible light from Earth (right) and from space in X-rays by satellites (left)

12. Radio wavelength observations are possible from Earth’s surface

13. The Very Large Array (VLA) in New Mexico

14. Differences in the temperature and density of small portions of Earth’s atmosphere cause passing starlight to quickly change direction, making stars appear to twinkle.

15. Image of stars taken with a telescope on the Earth’s surface. Same picture taken with Hubble Space Telescope high above Earth’s blurring atmosphere. Earth’s atmosphere hinders astronomical research

16. High above Earth’s atmosphere, the Hubble Space Telescope provides stunning details about the universe

17. Astronomers use different instruments to look at light of different wavelengths - sometimes, we even have to go above Earth’s atmosphere.

18. Not all EM radiation can penetrate Earth’s atmosphere.

19. Tutorial: Telescopes and Earth’s Atmosphere pg. 49 • Work with a partner! • Read the instructions and questions carefully. • Discuss the concepts and your answers with one another. Take time to understand it now!!!! • Come to a consensus answer you both agree on. • If you get stuck or are not sure of your answer, ask me or another group.

20. Which is the correct reasoning for why a gamma ray telescope located in Antarctica that is to be used to look for evidence of black holes in the centers of galaxies would not get funded? • There is no way to detect the presence of a black hole. • Gamma rays are too energetic to detect with a telescope. • You can’t build a functioning telescope in Antarctica. • Gamma rays don’t penetrate Earth’s atmosphere.

21. Imagine you’re the head of a funding agency that can afford to build only one telescope. Which of the three proposed telescopes below would be best to support? • A gamma ray telescope in Antarctica. • A radio telescope in orbit above the Earth. • A visible telescope located high on a mountain in Peru. • An ultraviolet telescope located in the Mojave desert.

22. McDonald Observatory (Fort Davis, TX)

23. A Few Astronomy Factoids (Or: So You Think You Want to be an Astronomer) • Research quality images are monochromatic. • Astronomy research is not the safest, but is much safer than it once was due to the use of CCDs over photographic plates. • Astronomy research is time consuming and expensive. • Astronomers spend more time in front of a computer than at a telescope. • Professional astronomers rarely ever actually look through an eyepiece.